A.
- For company A
Let
be the total cost that company A charges, and let
be the number of mattresses cleaned.
We know that Company A charges $30 per mattress and an additional $13 as service charges. so the total cost,
, will be the cost for the number of mattresses cleaned,
, plus the additional service charges. Putting all the things together, we get the equation:
- For company B
Let
be the total cost that company B charges, and let
be the number of mattresses cleaned.
We know that company B charges $28 per mattress and an additional $15 as service charges, so translating this into and equation we get:

Answer
Equations that represent Company A's and Company B's total mattress cleaning charges for a certain number of mattresses:
Company A:
Company B:

B.
Here we just need to replace
with 4 in both equations, evaluate them, and then compare the totals.
- For company A




Company A charges $133 for cleaning 4 mattresses.
- For company B




Company B charges $127 for cleaning 4 mattresses.
Answer
Company B charges less for cleaning 4 mattresses.
C.
Here we just need to replace
with 7 in both equations, evaluate them, and then subtract the Company's B total cost form Company's A total cost.
- For company A




- For company B




$223 - $211 = $12
Answer
We can save $12 by using the services of company B instead of company A.