Each course at Pease County Community College is worth either 3 or 4 credits. The members of the men's swim team are taking a total of 48 courses that are worth a total of 155 credits. How many 3-credit courses and how many 4-credit courses are being taken?

Hi Mary.

Let's let

x= number of three credit courses

y = number of four credit courses

x+y= 48

3x + 4y = 155

Youcan use either substitution or elimination to solve

Using elimination, multiply the first equation by -3.

This gives us

-3x-3y=-144

3x+4y= 155

Add these two equations together

y = 11

and therefore, x=37