Rob has 40 coins, all dimes and quarters. All his money equals $7.60, how much dimes and quarters does rob have? Show your work

Let d = the number of dimes. Then the number of quarters is (40-d). The dimes contribute 10d cents to the total. The quarters contribute 25*(40-d) cents to the total. The "value" equation is 10d + 25*(40-d) = 760. Simplify and solve for x: 10d + 1000 - 25d = 760, or -15d = 1000-660 ---> -15d = -240. d =  = 16. Answer. 16 dimes and 40-16 = 24 quarters. by ikleyn(36377)

Step-by-step explanation:

Let d = the number of dimes. Then the number of quarters is (40-d). The dimes contribute 10d cents to the total. The quarters contribute 25*(40-d) cents to the total. The "value" equation is 10d + 25*(40-d) = 760. Simplify and solve for x: 10d + 1000 - 25d = 760, or -15d = 1000-660 ---> -15d = -240. d =  = 16. Answer. 16 dimes and 40-16 = 24 quarters. by ikleyn(36377)