19. 7m + 10 + 9m = 16m + 10
7m + 9m + 10 = 16m + 10
16m + 10 = 16m + 10
20. 2b × 5 = 7b
10b ≠ 7b
21. 9(4r - 6) = 36r - 54
9(4r) - 9(6) = 36r - 54
36r - 54 = 36r = 54
22. 12 + 5(2 + y) = 5y + 22
12 + 5(2) + 5(y) = 5y + 22
12 + 10 + 5y = 5y + 22
22 + 5y = 5y + 22
23. 15j + 11 - 6j = 9j + 11
15j - 6j + 11 = 9j + 11
9j + 11 = 9j + 11
24. 8(3x + 1) = 24x + 1
8(3x) + 8(1) = 24x + 1
24x + 8 ≠ 24x + 1