3.2 to the power of 2 is what?

Multiply it by itself x times depending on the number of the exponent, so here the exponent is 2, so multiply 3.2 by itself 2 times so you get 3.2*3.2, You can then solve from there so 10.24 is your answer. 

The difference is 5,100m?

It is 6% because if you subtract 69-58=6 so 6% is the answer to your question.