How many vertices does a polyhedron composed of 12 faces and 30 edges have

How many vertices does a polyhedron composed of 12 faces and 30 edges have

This is a ten prism. N prism has 3N edges, N + 2 faces and 2n vertices, so it should have 20 vertices

Euler, a great mathematician, discovered and proved the formula about the relationship between the vertex (V), the number of edges (E) and the number of faces (f) of a polyhedron______ ．

Euler, a great mathematician, discovered and proved the formula V + F-E = 2 for the relationship among the vertex (V), edge number (E) and face number (f) of a polyhedron

Euler, a great mathematician, discovered and proved the formula about the relationship between the vertex (V), the number of edges (E) and the number of faces (f) of a polyhedron______ ．

Euler, a great mathematician, discovered and proved the formula V + F-E = 2 for the relationship among the vertex (V), edge number (E) and face number (f) of a polyhedron

What's the percentage of 78 divided by 1263

6.18%

How to write 4.2 divided by 35?

4.2÷7÷5=0.12

Solve the following equation and check (x + 0.6) * 3.2 = 64

3.2x+1.92=64
3.2x=64-1.92
3.2x=62.08
x=19.4
The checking calculation is to substitute x = 19.4 into the equation
（19.4+0.6）*3.2
=20*3.2
=64
correct!

Solve and check the following simple equation problems in grade five
1.4+x=6
2.x-5=8

1.4+x=6
x=6-4;
x=2;
Carry in test; X = 2; 4 + 2 = 6
2.x-5=8
x=8+5;
x=13;
Carry in test: x = 13; 13-5 = 8
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Solving + checking equation
Solve the equation and check it directly
1 x +2.87 =28.7
2 x-4.53=45.3
3 2.5x=60
4 1.8x=4.5
5 x/23=12
6 x/1.3=4.5
7 5x=80
8 7.2-9=12.6
9 6.6+3.5x=7.3
Checking examples:
For example, 2.5x-40 = 20
Checking calculation: the left side of the original equation is 5x-40 = 5x12-40 = 20, and the right side is 20. Because the left side is the right side, x = 12 is the solution of the original equation.
The problem above is checked in this way.

1.x +2.87 =28.7
x=25.83
Checking calculation: substitute x = 25.83 into the original equation, left = x + 2.87 = 25.83 + 2.87 = 28.7, right = 28.7, because left = right, so x = 25.83 is the solution of the original equation
2 x-4.53=45.3
X=49.83
Checking calculation: substitute x = 49.83 into the original equation, left = x-4.53 = 49.83-4.53 = 45.3, right = 45.3, because left = right, so x = 49.83 is the solution of the original equation
3 2.5x=60
X =24
Checking calculation: substitute x = 24 into the original equation, left = 2.5x = 2.5 × 24 = 60, right = 60, because left = right, so x = 24 is the solution of the original equation
4 1.8x=4.5
X=2.5
Checking calculation: substitute x = 2.5 into the original equation, left = 1.8x = 1.8 × 2.5 = 4.5, right = 4.5, because left = right, so x = 2.5 is the solution of the original equation
5 x/23=12
X=276
Checking calculation: substitute x = 276 into the original equation, left = x / 23 = 276 / 23 = 12, right = 12, because left = right, so x = 12 is the solution of the original equation
6 x/1.3=4.5
X=5.85
Checking calculation: substitute x = 5.85 into the original equation, left = x / 1.3 = 5.85 / 1.3 = 4.5, right = 4.5, because left = right, so x = 5.85 is the solution of the original equation
7 5x=80
X=16
Checking calculation: substitute x = 16 into the original equation, left = 5x = 5 × 16 = 80, right = 80, because left = right, so x = 16 is the solution of the original equation
8 7.2-9=12.6
There are no unknowns
9 6.6+3.5x=7.3
X=0.2
Checking calculation: substitute x = 0.2 into the original equation, left = 6.6 + 3.5x = 6.6 + 3.5 × 0.2 = 7.3, right = 7.3, because left = right, so x = 0.2 is the solution of the original equation

Let's talk about the solution and checking calculation of the following equations
x-1.5=4
5x=1.5
X divided by 1.1 = 3
example
x+0.3=1.8
Solution: x + 0.3-0.3 = 1.8-0.3
x=1.5
Test: left side of equation = x + 0.3
=1.5+0.3
=1.8
=On the right side of the equation

Sweat... Good trouble to say
According to your supplementary Amendment:
x-1.5=4
x-1.5+1.5=4+1.5
X=5.5
Test: left side of equation = x-1.5 = 5.5-1.5 = 4 = right side of equation
5x=1.5
5x÷5=1.5÷5
X=0.5
Test: left side of equation = 5x = 0.5 × 5 = 1.5 = right side of equation
x÷1.1=3
x÷1.1×1.1=3×1.1
X=3.3
Test: left side of equation = x △ 1.1 = 3.3 △ 1.1 = 3 = right side of equation

Check the following equation
X+35=75.8
368.5-X=21.6
6X=7.5
1.55÷X=0.5
X÷4=3.48

X + 35 = 75.8x = 75.8-35x = 40.8 test: substitute x = 40.8 into the original equation to get left = 40.5 + 30 = 75.8, right = 75.8, left = right, so x = 40.8 is the solution of the original equation 368.5-x = 21.6x = 368.5-21.6x = 346.9 test: substitute x = 346.9 into the original equation to get left = 368.5-346.9 = 21.6, right = 21.6, left = 21.6