Problem:
Lucky Larry's teacher asked him to substitute numbers for , and in the expression and evaluate the result. Larry ignored the parentheses but added and subtracted correctly and obtained the correct result by coincidence. The numbers Larry substituted for , and were , and , respectively. What number did Larry substitute for ?
Answer Choices:
A.
B.
C.
D.
E.
Solution:
The correct answer was . Larry's answer was . Therefore , so .
The problems on this page are the property of the MAA's American Mathematics Competitions