Love to write a complete standard solution, thank you 1、 4 (20-x) = 24 2, 0.3 (0.4-x) = 0.12 3. (7 + x) / 4 = 15

Love to write a complete standard solution, thank you 1、 4 (20-x) = 24 2, 0.3 (0.4-x) = 0.12 3. (7 + x) / 4 = 15

1、 4 (20-x) = 24
4×20-4×x=24
80-24=4x
56÷4=x
x=14
2、 3 (0.4-x) = 0.12
0.3×0.4-0.3×x=0.12
0.12-0.3x=0.12
0.12-0.12=0.3x
0=0.3x
x=0
3、 (7 + x) / 4 = 15
7/4+x/4=15
1.75+x/4=15
x/4=15-1.75
x/4=13.25
x=13.25×4
x=53

The circumference of a rectangle is 70cm, and its length is 1.5 times of its width. What is its area? It needs to be solved by equation

This problem involves the application of linear equation of one variable
First read the title and apply each number
The length is 1.5 times the width. Suppose the width is x cm, so the length is 1.5x
The circumference is 70cm. A linear equation of one variable can be listed as: (1.5x + x) * 2 = 70. Then x = 14. That is, the length is 21 and the width is 14
Area: S = length x width = 21 * 14 = 294 square centimeter

Divide two numbers, the quotient is 8 and the remainder is 11. Add the divisor, the divisor, the quotient and the remainder, and the sum is 543?