If Denali has 11 quarters and dimes in his pocket, and they have a combined value of 215 cents, how many of each coin does he have?

Answer 1

Let x = number of dimes. Then 11-x = number of quarters

0.10x + 0.25(11 - x) = 2.15

Solve for x.

Answer 2

Let X=number of quarters and Y=number of dimes. We now have 2 equations we can create from the information provided.

X+Y=11

25X+10Y=215

From here, we want to try to eliminate one of the two variables so lets take the first equation and multiply it by 10. We now have 10X+10Y=110. Subtract this equation from the second equation and we get 15X=105. Divide each side and we get X=7. We can then go back to our original equation and see that if X is 7, Y must be 4. For completeness, lets plug both values into the second equation and make sure it is still correct.

25(7)+10(4)=175+40=215 so we konw we are correct. Hope this helps!

Answer 3

10D + 25Q = 215

D + Q = 11

multiply both sides by 10

10D + 10Q = 110

subtract the 3rd equation above from the 1st

15Q = 105

Q= 105/15

Q = 7 Quarters

D=11-7 = 4 Dimes