Nothing I find in my notes or online doesn't show me how to solve this. I know how to set it up, but ain't letting me submit 2 pics.

Can someone me out here number 4 plz

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

This is a map of the mars exploration rover opportunity predicted landing site on mars. the scale is 1cm : 9.4km. what are the approximate measures of the actual length and width of the ellipse? i mostly need to know how to set it up : )