Kat has 19 coins, all quarters and dimes, that are worth a total of $4. The system of equations that can be used to the number of quarters,q, and the number of dimes,d, she has shown
q + d=19
0.25q + 0.1d=4
(d)
-0.1(q + d=19)
0.25q + 0.1d=4
Opposites cancel
-0.1q -0.1 d=1.9
0.25q + 0.1d=4