A quiz had some 3-point and some 4-point questions. A perfect score was 100 points. Find out how many questions were of each type if there were a total of 31 questions on the quiz

I have no clue how to start this.

1 answer

X 3-pt questions.
(31-x) 4-pt question.

3x + 4(31-x) = 100 Points.
3x + 124 -4x = 100
-x = 100-124 = -24

X = 24. 3-pt questions.
(31-x) = 31-24 = 7 4-pt questions.