1) 
2) 21
3) 13.125
4) 0.5
5) 1.5
Пошаговое объяснение:
1)
13 * 10 = x * 15
x = (13 * 10) / 15
x =
2)
24 * 7 = 8 * x
x = (24 * 7) / 8
x = 21
3)
8 * x = 15 * 7
x = (15 * 7) / 8
x = 13.125
4)
x * 4 = 2/3 * 3
x = (2/3 * 3) / 4
x = 0.5
5)
10 * 3x = 9 * 5
30x = 45
x = 1.5
