Question

Colton works at an electronics store as a salesperson. Colton earns a 7% commission on the total dollar amount of all phone sales he makes, and earns a 3% commission on all computer sales. Colton had twice as much in phone sales as he had in computer sales and earned a total of $85 in commission. Write a system of equations that could be used to determine the dollar amount of phone sales Colton made and the dollar amount of computer sales he made. Define the variables that you use to write the system.
Answer
Attempt 1 out of 2

Let
equals=
.
Let
equals=
.
System of Equations:

Answer 1

Let P = dollar amount of phone sales, and C = dollar amount of computer sales.

System:
P = 2C
0.07P + 0.03C = 85

(Equivalently, multiply the second equation by 100: 7P + 3C = 8500.)

If you want the amounts: substituting P = 2C gives 0.14C + 0.03C = 85 → 0.17C = 85 → C = $500, P = $1000.