Set up a system of linear equations for each problem then solve

Question

I am giving you a test worth 100 points containing 40 questions. There are two-point and four-point questions on the test. How many of each type of question are on the test???

Answer 1

100 points 40 questions some 2 point questions, some 4 point questions. how many of each?

2x + 4(40-x) = 160 -2x = 100

80 - x = 50

x = 30 two point question, 10 four point questions