If we assume that x isthe number of multiple choice questions, and y is the number of word problems, we can write a system of equations like: { x + y = 38 { 2x + 5y = 100
If we multiply the first equation by -2 we get: { -2x-2y = -76 { 2x + 5y = 100
Now if we add both equations we get only equation with 1 unknown (y) :
3y = 24 ⇒ y = 8
Substituting the calculated value to the first equation we get:
x + 8 = 38 ⇒ x = 30
The solution: { x = 30 { y = 8
means that: The test had 30 multiple choice questions, and 8 word problems.
