Answer:
? = 14
Explanation:
let us say that ? = x
7^x * 7^5^4 = 7^34
When you have a power to a power you multiply
7^x * 7^20 = 7^34
when you multiply common bases you add the power. since all the bases aer the same just look at the power
7^34-20 = 7^x
7^14 = 7^x