Eric would like to buy a new math folder for $2.22 and a case of mechanical pencils for $2.95. He would also like to buy sticker
2 answers:
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7x-y=9
3x-y=5 (multiply by -1 both sides of the equation)
7x-y=9
-3x+y=-5 (now add both equations)
7x-3x-y+y=4
4x=4 (divide by 4 both sides of the equation)
x=1
y=3x-5=3×1-5=-2
y= -2
answer: x=1, y=-2