how many pounds of substance a, which costs $2 per pound, must be mixed with 18 pounds of substance b, which costs $2.40 per pound, to create a mixture which will cost $2.08 per pound

Answer 1

2a + 2.4(18) = 2.08(18+a)

2a + 43.2 = 37.44 + 2.08a

.08a = 43.2 - 37.44 = 5.76

a = 5.76/.08 = 72 pounds of substance a

mixed with 18 pounds of b to create

90 pounds of a mixture costing $2.08 per pound

2(72) + 2.4(18) = 144 + 43.2 = 187.2 = 2.08(90)= 187.2