5x+4X-0.24=0.66.

5x+4X-0.24=0.66.

The original equation is transferred to 5x + 4x = 0.66 + 0.24
9x = 0.9
The coefficient of 1 is x = 0.1

x+y=80 5x+2.5y≤290 1.5x+3.5y≤212

∵x+y=80
The following two inequalities (1) and (2) are substituted with x = 80-y
（1） 5x+2.5y≤290
5(80-y)+2.5y≤290
y≥44
（2） 1.5x+3.5y≤212
1.5(80-y)+3.5y≤212
y≤46
From (1) and (2), 44 ≤ y ≤ 46
∴-44≥-y≥-46
∴80-44≥80-y≥80-46
∴36≥x≥34
Answer: 34 ≤ x ≤ 36,44 ≤ y ≤ 46

Y-1 / 5Y = 5.6

0.8y=5.6
y=7

Solve the equation 3 / Y-1 + 5y-2 / y2-y = 6 / y

Multiply both sides by Y (Y-1)
3y+5y-2=6y-6
2y=-4
y=-2
Test: y = - 2 is the solution of the equation

To solve the equation, 2 (10-0.5y) = 1 (1.5y + 2)

5x + 10Y = 42 and 10x + 5Y = 30

5x+10y=42
10x+5y=30
2x+y=6
y=6-2x
5x+10(6-2x)=42
5x+60-20x=42
15x=18
x=6/5
y=18/5

5x-5y = - 12 - 2x + 10Y = 16

5x-5y=16
-12-2x + 10Y = 16 can be changed into x-5y = 14
It's like this
The sum of the two formulas is: 6x = 30, that is, x = 5
So I substitute y = 9 / 5

Solving equations: - 5x + 5Y = 15 4x + 10Y = - 2

:-5x+5y=15 -x+y=3,-4x+4y=12,
4x+10y=-2,14y=10,
y=5/7,x=-16/7

How to solve the equations of 2.5x + 2.5Y = 400 and 10y-10x = 400;

Because 2.5x + 2.5Y = 400, so x + y = 160, because 10y-10x = 400, so Y-X = 40. Add the two simplified formulas to 2Y = 200, so y = 100, x = 60

5x-5y=-12 -3y+10y=16
This is not the original equation. Let's calculate this 0
2 / 3 (X-Y) - 4 / 4 (x + y) = - 1
6（x+y）-4（2x-y）=16

This is not the original equation. Let's calculate this 0 0,
2 / 3 (X-Y) - 4 / 4 (x + y) = - 1
6（x+y）-4（2x-y）=16
8(x-y)-3(x+y)=-12
6(x+y)-4(2x-y)=16
5x-11y=-12.(1)
-2x+10y=16.(2)
(1)*2+(2)*5
28y=56
y=2
Substitute (1) to get
5x-22=-12
5x=10
x=2
Solution
x=2
y=2