Solved by pluggable solver: SOLVE linear system by SUBSTITUTION |
Solve: into another equation: Answer: |
Let "d" be the number of dimes. Then the number of nickels is d+5, according to the condition. Then the number of quarters is (35 - d - (d+5)) = 35 - 2d -5 = 30 - 2d. Nickels contribute 5*(d+5) cents to the total. Dimes contribute 10d cents to the total. Quarters contribute 25*(30-2d) cents to the total. An equation for the total is 5*(d+5) + 10d + 25*(30-2d) = 600 cents. Simplify it: 5d + 25 + 10d + 750 - 50d = 600, 5d + 10d - 50d = 600 - 25 - 750, -35d = -175 ---> d == 5. There were 5 dimes. Now you find all remaining unknowns.