Question

Anna has $45 to spend on felt to make banners for an upcoming game. Gold felt costs $5 per yard and blue felt costs $4 per yard. Anna needs at least 7 yards of felt to make the banners. Which is a solution for this situation?

Answer 1

For this case you must make a system of equations that suits the situation you want to solve.
We have then:
x: Gold felt
y: Blue felt
Writing the system of equations:
x + y> = 7
5x + 4y = <45
Solving the system of equations:
Step 1: Multiply equation 1 by -4
-4x -4y = -28
5x + 4y = 45
Step 2: add equations:
x = 45-28
x = 17
Clearing y:
y = 7-x = 7-17 = -10
y = -10
answer
You can buy between 7 and 9 Gold felt