Volunteers at Sam's school use some of the student council's savings for a special project. They buy 3 backpacks for $4 each and fill each backpack with paper and pens that cost $4. By how much did the
student council's savings change because of this project?
The savings was changed by
dollars.

The value of x in this system of equations is 1. 3x + y = 9 y = –4x + 10 substitute the value of y in the first equation: combine like terms: apply the subtraction property of equality: apply the division property of equality: 3x + (–4x + 10) = 9 –x + 10 = 9 –x = –1 x = 1 what is the value of y?