College Credit

Question

Each course at Mt. Regis 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 155 credits. How many 3-credit courses and how many 4-credit courses are being taken? 

Answer 1

We know there are 48 courses in all, "x" worth 3 credits and (48-x) worth four credits.  Note that we need only one variable.

3x + 4 * (48-x) = 155

 

3x + 192 - 4x = 155

 

x = 37

So there are 37 3-credit courses and 11 (48-37) 4-credit courses.

Check:  37*3 + 11*4 = 111 + 44 = 155