Let D be the number of dimes and Q be the number of quarters.
We know that the number of dimes multiplied by their value summed with the number of quarters multiplied by their value will amount to $2.25. Written mathematically:
0.10*D + 0.25*Q = 2.25
We also know that there are twice as many dimes as there are quarters, which translates to D = 2Q. So we substitute that into our previous equation:
0.10*(2Q) + 0.25*Q = 2.25
0.20*Q + 0.25*Q = 2.25
Q = 2.25/0.45
Q = 5 quarters
Since we know that D = 2Q: D = 2*(5) = 10 dimes
