Algebra 1 quizz

Question

Diego is attending UTEP and has completed some courses worth 3 credits and some courses worth 4 credits. He has earned a total of 59 credits after completing 18 courses.

How many courses worth 4 credits has Diego completed?

Answer 1

Let's define the following variables:

x: number of 3 hour courses

y: number of 4 hour courses

The statement, " He has earned a total of 59 credits after completing 18 courses" gives us our two equations:

3x + 4y = 59

x + y = 18

We can multiply everything in the second equation by - 3 to get the x-terms to have opposite coefficients:

3x + 4y = 59

-3x - 3y = 54

If we then add like-terms together, we get:

y = 5, so he has taken 5 four-hour courses.