Linear Equations

Question

You want to buy either a Blu-Ray disc or DVD as a present for a total of 15 people. Blu-ray discs cost $20 each and DVDs cost $8 each. Write a linear equation in one variable for the total cost and then determine how much money must be spent if 6 people get Blu-ray discs

Answer 1

b represents the number of Blue-Ray

20 - b represents the number of DVD

20b + 8(20 - b) = C(b)

Substitute 6 for b and answer?