To isolate b, add a and subtract c to the entire equation:
D - a + c = -b
Muliply b by -1 to eliminate the negative:
-D + a - c = b
Normal price for 5 pages: number of pages times the price per page
(5)*($8.75) = $43.75
Discounted rate: $8.75 - $1.45 = $7.30
Discounted price for 5 pages:
(5)*($7.30) = $36.50
Answer:

Step-by-step explanation:
You will use the FOIL method, which is very similar to the distributive property.
In order to do multiply correctly, multiply the y by 3x, 5y, and -2. You should get:

Then multiply the -4 by 3x, 5y, and -2 where you should get:

By using the foil method, you got rid of the parentheses. Now you can simply combine like terms and get your final answer:

I hope this helps you!