Meghdad consumes only two goods, chicken strips (C) and hamburgers (H) and considers them to be perfect substitutes, as shown by his utility function: U(C, H) = 2C + 4H. The price of chicken strips is $6 and the price of hamburgers is $4, and Meghdad's monthly income is $400. Meghdad's friend gives him a birthday gift certificate of $60 redeemable only at chicken strips. His friend could have made him exactly as happy by spending far less. His friend would have needed to give him $______ in cash to make him just as well off as before. Fill in the blank.