Answer: For each birdhouse built, the total cost increases by $3.50.
Step-by-step explanation:
Given: The total cost for Sophia to build b birdhouses is represented by the function
We can see in the function 3.5 is multiplied to b, so when b increases , f(b) increases by 3.5.
and
Therefore, the value of 3.5 represents that for each birdhouse built, the total cost increases by $3.50.