a = 2 pt, b = 4 pt, c = 5 pt
a + b + c = 28
2a + 4b + 5c = 100
a = 2c
2a + 2b + 2c = 56
... substituting ... 3a + 2b = 56
4a + 8b + 10c = 200
... substituting ... 9a + 8b = 200
subtract the equations (after multiplying) to eliminate b
On a 28-question test, there are 2-point questions, 4-point questions, and 5-point questions. The test is worth a total of 100 points. There are twice as many 2-point questions as 5-point questions on the test. How many 2-point questions are on the test?
1 answer