Xbox 360 and lunzzotoon worth

What is the value of x? enter your answer in the box. photo attached.

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?

Assume that y varies inversely with x. if y=1.6 when x=0.5 find x when y=3.2