how do you do this question

Question

(3^-3 + 3^-4)/3^-5

Answer 1

3^-3 + 3^-4 = 3*3^-4 + 3^-4
= (3+1)*3^-4 = 4*3^-4

Recall that a negative exponent switches between top and bottom in fractions. So,

4*3^-4/3^-5 = 4/3^4 * 3^5 = 4*3 = 12