1959 AHSME Problems/Problem 29
Problem 29
On a examination of 
questions a student answers correctly 
of the first 
. Of the remaining questions he answers one third correctly.
All the questions have the same credit. If the student's mark is 50%, how many different values of can there be?
Solution
To calculate the student's score in terms of , you can write the following equation:
\frac{\frac{n-20}{3} + 15}{n} = \frac{1}{2}
n=55$, so there is one solution.
