If Jenny sells three pencils and buys an eraser, she is up ten cents.
If instead Jenny sells five pencils and buys two erasers, she breaks even.
How much is a pencil?
How much is an eraser?
Solution to the Problem:
A pencil costs 20 cents and an eraser costs 50 cents.Let p = cost of a pencil.
Let e = cost of an eraser.
Then 3p - e = 10
and 5p - 2e = 0.
Multiply the first equation by -2 and add to the second equation:
Multiplying by -2: -6p + 2e = -20
Then adding to the second equation: -p = -20.
Therefore, p = 20 and e = 50.
Correctly solved by:
| 1. James Alarie | Flint, Michigan |
| 2. John C. Funk | Ventura, California |
| 3. Tyler Cantrell |
Mountain View High School, Mountain View, Wyoming |
| 4. Halee Salsbury |
Mountain View High School, Mountain View, Wyoming |
| 5. Erin Watson |
Mountain View High School, Mountain View, Wyoming |