6
Like how

= 36
Square root does the opposite.
Edit: my mistake, it is 6
Since there are no specific requirements given other than expression written using exponents, I am just going to give some examples.
1. 5x^2 - 3
2. 8^5 - 15x + 7
3. 15x^10 - 8x^7 + 16x^5 + 17^3 - 4^2 +13x - 2
.75 for the first question
75% for the second question


No, since 0 doesn't belong to the domain.