75:(2х)=15:25 44:99=4:(3х) (5х):13=8:52 10,5:21=(4х):20

Question

75:(2х)=15:25

44:99=4:(3х)

(5х):13=8:52

10,5:21=(4х):20

Answer 1

2х *15  = 75 * 25
30х = 1875
    х = 62,5
--------------------------
3х * 44 = 99 * 4
132х = 396
      х = 3
-------------------------
5х * 52 = 13 * 8
260х = 104
      х = 0,4
-------------------------
4х * 21 = 10,5 * 20
84х = 210
    х = 2,5

Answer 2

1)
75 : 2х = 15/25
75 : 2х = 3/5
2х = 75 × 3/5
2х = 45
х = 22,5

2)
44:99 = 4 : 3х
44/99 = 4/3х
4/9 = 4/3х
4×3х = 9 × 4
12x = 36
x = 3

3)
5x : 13 = 8:52
5x/13 = 8/52
5x/13 = 2/13
5x × 13 = 13 × 2
65x = 26
x = 0,4

4)
10,5 : 21 = 4x : 20
10,5/21 = 4x/20
10,5 × 20 = 21 × 4x
210 = 84x
x = 2,5