Question

20: 5=2x , 36: =2x2 , 24:3 : 4 ,3x =5x6 , :5=20:4 , 21: =15:5

Answer 1

20:5=2x 
4=2x
x=4:2
x=2
...........................
36:a=2x2
36:a=4
a=36:4
a=9
..........................
24:3:4=
8:4=2
...................................
3x=5x6
3x=30
x=30:3
x=10
............................
a:5=20:4
a:5=5
a=5x5
a=25
................................
21:a=15:5
21:a=3
a=21:3
a=7

Answer 2

20:5=2x      2x=4    x=4:2    x=2
36:x=2*2     4x=36     x=36:4     x=9
3x=5*6      x=30:3    x=10
x:5=20:4      x=5*5   x=25
21:x=15;5      21;x=3      3x=21    x=21;3   x=7