3+5=5+3

13=10+3

8-4=3-2

x + 5 = 5 + x

5+k = 5.k

7y + 4 = 4y + 7

4.(a+2) = 2a +2a + 4 + 4

x = 5 ise 5.x = 10

9m + m = 10m

90 = 10 + 80