Answer:
Cost of one bundle of shingles is $20 and cost of one roll of roofing paper is $110.
Step-by-step explanation:
Let the cost of each bundle of shingles = x
And cost of the roofing paper = y
Contractor buys 30 bundles of shingles and 4 rolls of roofing paper for $1040.
30x + 4y = 1040
15x + 2y = 520 -----(1)
In a second purchase contractor buys 12 bundles of shingles and 16 rolls of roofing paper for $2000
12x + 16y = 2000
3x + 4y = 500 --- (2)
Equation (1) multiplied by 2 then subtracted from equation (2)
(3x + 4y) - 2(15x + 2y) = 500 - 1040
(3x - 30x) + (4y - 4y) = -540
-27x = -540
x = 20
From equation (1)
15(20) + 2y = 520
300 + 2y = 520
2y = 220
y = 110
Therefore, cost of one bundle of shingles is $20 and cost of one roll of roofing paper is $110.