Question

Ecuaciones:
9x + 12 = 3x
3x + 7 = 25
1/2x + 1/4 = 2/5 + 7/8x
12x + 7 - 19x = 22
7x + 5 = 19x

Answer 1

9x+12=3x        3x+7=25
9x-3x=-12       3x=25-7
6x=-12             3x=18
x=-12/6            x=18/3
                        x=6

12x+7-19=22      7x+5=19x
12x=22-7+19      7x-19x=-5
12x=34               -12x=-5   *(-1)
x=34/12               12x=5
x=17/6                  x=5/12