Solid paper costs 1.75 each
Printed paper costs 2.50 each
Given:
Ben = $43.50 (12 rolls solid paper and 9 rolls of printed paper)
Joel = $51.50 (8 rolls solid paper and 15 rolls of printed paper)
Let x = solid paper
Let y = printed paper
12x + 9y = 43.50
8x + 15y = 51.50
Find x:
8x + 15y = 51.50
8x = 51.50 - 15y
x = (51.50 - 15y)/8
Substitute x:
12x + 9y = 43.50
12(51.50 - 15y)/8 + 9y = 43.50
(618 - 180y)/8 + 9y = 43.50
8 (618 - 180y)/8 + 8*9y = 43.50 * 8
618 - 180y + 72y = 348
-108y = 348 - 618
-108y = -270
-108y/-108 = -270/-108
y = 2.50
x = (51.50 - 15y)/8
x = (51.50 - 15(2.5) /8
x = (51.50 - 37.50)/8
x = 14/8
x = 1.75
To check: x = 1.75 ; y = 2.5
12x + 9y = 43.50
12(1.75) + 9(2.5) = 43.50
21 + 22.50 = 43.50
43.50 = 43.50
8x + 15y = 51.50
8(1.75) + 15(2.5) = 51.50
14 + 37.50 = 51.50
51.50 = 51.50
