(1/5)^21-2x =25^3x+7

Question

(1/5)^21-2x =25^3x+7

Answer 1

5^(- (21 - 2x)) = 5^(2(3x + 7)) 
- (21 - 2x) = 2(3x + 7)
2x - 21 = 6x + 14
2x - 6x = 21 + 14
- 4x = 35
x = - 8,75