Question 514801
Since you're using the absolute value function, you need to solve:
-3x+7 = 9
and
-3x+7 = -9
.
-3x + 7  = 9
-3x = 2
x = -2/3
.
-3x +7 = -9
-3x = -16
x = 16/3
.
check to ensure both answers are correct.
.
-3(-2/3) + 7 = ??
+6/3 +7 = 2 + 7 = 9
correct
.
-3(16/3) + 7 = ??
-48/3 + 7 = -16 + 7 = -9
correct
.
Answer:  x = -2/3 or 16/3
.
Done.