tolong nomer 2&3. makasih

3. a, 12x+5 = 8x+21
12x-8x = 21-5
4x = 4
x = 4:4
x=1

b, 2(4x-3) = 3(2x+4)
8x-6 = 6x+12
8x-6x = 12+6
2x = 18
x = 18:2
x = 9

3) 12x + 5 = 8x + 21
12x - 8x = 21 - 5
4x = 16
x = 16/4
x = 4
maaf kalau salah