Can anyone help me solve the boxes that are blank?
I really appreciate it!

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

If 30 lb of rice and 30 lb of potatoes cost ? $27.60? , and 20 lb of rice and 12 lb of potatoes cost ? $15.04? , how much will 10 lb of rice and 50 lb of potatoes? cost?

Multiplying fractions by whole number 5 x 1/3=?