having hard time

Peter consumes only apples and bananas. Her income is $40 per week. The price of apples is SI and the price of bananas is $2. Her utility function is U = 10AB, where A is the quantity of apples she consumes in a week and B is the quantity of bananas. a) Write out Peter budget constraint and draw it on the grid. b) What is Peter marginal rate of substitution (MRS)