Answer:
The expected total cost of a service call for 6 hours of labor at company B is $239.5
Explanation:
To solve this, we'll find the expression that models the cost at company B.
First, we'll calculate the hourly rate. We know that is 25% greater than the $28 rate from company A, so we can use a rule of three as following:
This way,

Therefore, we'll have that the hourly rate for company B is $35.
Now, we know that the charge for service is $3 less than at company A. This way,

We can conclude that the charge for service at company B is $29.5
Using this data, we'll have that the expression that models the cost for company B is:

Using x = 6 (six hours of labor),

Therefore, we can conclude that the expected total cost of a service call for 6 hours of labor at company B is $239.5