A contractor combined x tons of a gravel mixture that contained 10% gravel G, by weight, with y tons of a mixture that contained 2% gravel G, by weight, to produce z tons of a mixture that was 5% gravel G, by weight. What is the value of x?
1) y = 10
2) z = 16
OA is D. I understand why statement 1 is sufficient, but not why statement 2 is sufficient.
My reasoning:
Statement 1 -->
10x + 2(10) = 5(x + 10)
10x + 20 = 5x + 50
5x = 30
x = 6
Statement 2 -->
10x + 2y = 5(16)
10x +2y = 80
We're left with two variables. Can we then use the equation x + y = 16 to solve for x?
1) y = 10
2) z = 16
OA is D. I understand why statement 1 is sufficient, but not why statement 2 is sufficient.
My reasoning:
Statement 1 -->
10x + 2(10) = 5(x + 10)
10x + 20 = 5x + 50
5x = 30
x = 6
Statement 2 -->
10x + 2y = 5(16)
10x +2y = 80
We're left with two variables. Can we then use the equation x + y = 16 to solve for x?
