A physics test has twenty questions worth 100 points. The test consists of true /false questions worth 3 points each and multiple choice questions worth 11 points each. How many multiple choice questions are on the test ?

Answer 1

number of T/F questions --- x
number of multiple choice --- 20-x

3x + 11(20-x) = 100
3x + 220 - 11x = 100
-8x = -120
x = 15

15 T/F questions and 5 multiple choices

Answer 2

If Mr.Chiko earns N$ x in a week and spend N$ y, what part of his weekly salary did he save?