Answer:
x = -1
Step-by-step explanation:
7^(3x+7) = 7^(-8x-4)
First Step: Cancel out like bases.
3x + 7 = -8x - 4
Second Step: Add 8x on both sides.
11x + 7 = -4
Third Step: Subtract 7 on both sides.
11x = -11
Fourth Step: Divide by 11 on both sides.
x = -1