Explanation:
8.
1/2(x + 24) = 21
1/2x +12 = 21
1/2x = 9
x = 18
9.
28 - 3x - 4 = 2x + 12 + x
24 - 3x = 3x + 12
24 - 6x = 12
-6x = -12
x = 2
10.
3x - 18 + 6 = 5x - 6
3x - 12 = 5x - 6
-2x - 12 = -6
-2x = 6
x = -3
hope it help.
can you answer my question, i can help you in math, can you help me in english? please