PLEASE HELP WITH 6&7 WILL GIVE BRAINLESIT

Ineed to know the answer to this algebra question.

Kayla and alberto are selling fruit for a school fundraiser. customers can buy small boxes of grapefruit and large boxes of grapefruit. kayla sold 3 small boxes of grapefruit and 1 large box of grapefruit for a total of $65. alberto sold 1 small box of grapefruit and 1 large box of grapefruit for a total of $55. what is the cost each of one small box of grapefruit and one large box of grapefruit?

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