Which shows the correct simplification of product of powers?

1.) 78 · 7-4 = 78· (-4) = 7-32

2.) 78 · 7-4 = 78 : (-4) = 7-2

3.) 78 · 7-4 = 78 + (-4) = 74

4.) 78 · 7-4 = 78 - (-4) = 712

The power symbols are missing.

I can infere that the product intended to simplify is (7^8) * (7^-4)., because that permits you to use the rule of the product of powers with the same base.

That rule is that the product of two powers with the same base is the base raised to the sum of the powers is:

(A^m) * (A^n) = A^ (m+n)

=> (7^8) * (7^-4) = 7^ [8 + ( - 4) ] = 7^ [8 - 4] = 7^4, which is the option 3 if the powers are placed correctly.