Grid-Ins
Student-Produced Response
The sum of r and p is equal to twice s, and p is 36 less than twice the sum of r and s. What is the value of r ?
Correct Answer: 12
Explanation:
The phrase "the sum of r and p is equal to twice s" can be written as r + p = 2s. The phrase "p is 36 less than twice the sum of r and s" can be written as p = 2(r + s) - 36. From the first equation, p = 2s - r. Substituting this expression for p into the second equation yields
| 2s - r | = | 2(r + s) - 36 |
| 2s - r | = | 2r + 2s - 36 |
| -r | = | 2r - 36 |
| -3r | = | -36 |
| r | = | 12 |
The value of r is 12.
(from the October 12, 1999 test)