Can You please explain how it works (if you can...)

What numbers are included in the set of integers? what numbers are not included?

Prove that the value of the expression 7^8–7^7+7^6 is divisible by 43.

Sean is his dad build a tiled walkway in their backyard. the walkway will be 6060 feet long and 22 feet wide. the local hardware store sells tiles which are 22 by 22 feet and come in boxes of 66. how many boxes of tiles do they need?