Question

You want to prepare a test that contains 20 questions worth 50 points overall. How many 2-point and 4-point questions can you include in the test?
a) 5, 10
b) 10, 10
c) 12, 8
d) 15, 5

Answer 1

treat them as ordered pairs. you want 2x+4y=50
x+y=20

so we can cancel the choices where there aren't 20 questions in total (a: 5+10=15)
now find which one of b,c, or d fits 2x+4y=50

Answer 2

so d then?

Answer 3

thnx

Answer 4

yeah