Question

The number of DVDs sold at a store in a month was 925 and the number of DVDs sold decreased by 12 per month. The number of Blu-ray discs sold in the same store in the same month was 507 and the number of Blu-ray discs sold increased by 26 per month. Let d represent the number of discs sold and t represent the time in months.

Write a system of equations by filling in the blanks:
d= _ t+ _
d= _ t+ _
Solve the system of equations using the substitution method. Complete the sentence to describe the solution.
There will be _ DVDs and Blu-Ray discs sold per month in _ months

Answer 1

• See below

Explanation:

DVDs

• d = 925 - 12t

Blu-rays

• d = 507 + 26t

Solve the system:

• 925 - 12t = 507 + 26t
• 26t + 12t = 925 - 507
• 38t = 418
• t = 418/38
• t = 11

Number of disks sold in 11 months:

• 925 - 12*38 = 469

There will be 469 DVDs and Blu-Ray discs sold per month in 11 months