Question

coffee a normally costs 75© per pound. it is mixed with coffee b which normally costs 80© per pound, to form a mixture that costs 78© per pound. if there are 10 pounds of the mix, how many pounds of coffee a were used in the mix?

Answer 1

Quantity equation =A+B=10 pounds
value equation=75A+80B=78*10 cents
Multiply through the quantity equation by 80
80A+80B=80*10
75A+80B=78*10
Subtract and solve for A
5A=2*10=20
5A=20
A=4 pounds(amount of A needed in the mix)

Answer 2

Quantity equation =A+B=10 pounds
value equation=75A+80B=78*10 cents
Multiply through the quantity equation by 80
80A+80B=80*10
75A+80B=78*10
Subtract and solve for A
5A=2*10=20
5A=20
A=4 pounds(amount of A needed in the mix)