Условие:

Реши уравнения.
72 − x = 18 * 3;
x : 8 = 130 + 270;
400 : x = 1000 : 10;
x − 290 = 470 + 230;
x + 320 = 90 * 8;
15 * x = 630 : 7.

72 − x = 18 * 3
72 − x = 54
x = 72 − 54
x = 18
 
x : 8 = 130 + 270
x : 8 = 400
x = 400 * 8
x = 3200
 
400 : x = 1000 : 10
400 : x = 100
x = 400 : 100
x = 4
 
x − 290 = 470 + 230
x − 290 = 700
x = 700 + 290
x = 990
 
x + 320 = 90 * 8
x + 320 = 720
x = 720 − 320
x = 400
 
15 * x = 630 : 7
15 * x = 90
x = 90 : 15
x = 6