 |
| ||
| |||
|
| Math Central | Quandaries & Queries |
|
Question from hannah, a student: i have 23.50 in quarters and dimes. if i have 15 more dimes than two times the amount of quarters i have, how many coins do i have total? |
Hi Hannah,
Suppose I have D dimes and Q quarters. The total value is $23.50 or 2350¢. Thus
10 D + 25 Q = 2350
You have 15 more dimes then twice the number of quarters. Twice the number of quarters is 2Q so
2Q + 15 = D
Substitute this expression for D into the first equation to get
10 (2Q + 15) + 25 Q = 2350
20 Q + 150 + 25Q = 2350
45Q = 2350 - 250 = 2200
Q must be an integer but 45 does not divide 2200 so there is something wrong with this question.
Penny
| ||
| ||
| ||
 |
 |
|
Math Central is supported by the University of Regina and The Pacific Institute for the Mathematical Sciences.