Question

Your teacher is 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

30 questions worth 2 points, and 10 questions worth 4 points.

Answer 2

Since we're looking for x and y, we can set up a system of equations.
x + y = 40
2x + 4y = 100
Let's try 20 for x and 20 for y.
20 + 20 = 40
2(20) + 4(20) =40 + 80, nope.
Let's try 30 for x and 10 for y.
30 + 10 = 40
2(30) + 4(10) = 60 + 40, yes!
x (2 pt) = 30
y (4 pt) = 10
I hope this helps!