A researcher has two base solutions, a 10% base solution and a 40% base solution. For her experiment, she needs to make 130 mL of a 32% base solution. This final mixture contains x mL of the 10% base solution and y mL of the 40% solution. Which of the following choices represents an expression for the volume of the 40% solution that is needed to make the final mixture?
y = 130x
y = x - 130
y = 130 + x
y = 130 - x
