x: 21 = 0.8:14 solution ratio

x: 21 = 0.8:14 solution ratio

x：21=0.8：14
14x=21×0.8
14x=16.8
x=16.8÷14
x=1.2

The solution ratio is 0.8 x = 21 14

0.8 x = 14 / 21
x/0.8=14/21
x/(4/5)=2/3
x*5/4=2/3
x=2/3*4/5
x=8/15

8 / 21 = 0.4: X

8/21=0.4:x
x=0.4÷8/21
x=1.05

-3 / 4 + (- 1 / 6) + 3 / 8 - (- 5 / 12) to solve the equation
Calculation ==

=-18 / 24-4 / 24 + 9 / 24 + 10 / 24
=-3 / 24
=-One in eight

Solving equations with Unknowns at both ends
For example: (x + 360) * 1 / 4 = 1 / 2x-30
*=Multiply sign
4 / 1 = quarter

The solution equation with three unknowns
{x+y+z=20
3x+2y+z=50
Quick! Thank you!

It should also have some constraints, otherwise it is not easy to solve!

Unknowns - 0.3 unknowns = 21. Solve the equation

Unknowns - 0.3 unknowns = 210.7 unknowns = 21 unknowns = 21? 7 unknowns = 30 please adopt, your adoption is my motivation,

(solution ratio) (5.4:1.8 = x: 15) (8: x = 1 / 3:1 / 16) (7 / 15 = 75)

5.4：1.8=x：15
1.8x=15×5.4
1.8x=81
x=45
8: X = 1 / 3:1 / 16
1/3x=1/16×8
1/3x=1/2
x=1.5
7 out of 15 = x out of 75
15x=75×7
15x=525
x=35

Practical problems solved by proportion or equation in Grade 6 (a little more difficult)

A school has three extracurricular interest groups: mathematics, meteorology and aeromodelling. The number of the mathematics group is one third of the total number of the three groups. The number of the aeromodelling group is three less than that of the meteorology group. The ratio of the number of the meteorology group and the aeromodelling group is 4:3

How to calculate 234 * 52 + 234 * 16 + 166 * 68

234*52+234*16+166*68
=234*（52+16）+166*68
=234*68+166*68
=（234+166）*68
=400*68
=27200