Please helppp no bias answer please

X2 + y 2 = 36 x + y = 6 solve the system of equations.

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

At the beginning of year 1, carlos invests $600 at an annual compound interest rate of 4%. he makes no deposits to or withdrawals from the account. which explicit formula can be used to find the account's balance at the beginning of year 5? what is, the balance?