Answer:
f(c) =17.12c -14.56c + 5.40(.5c) - 1.20(.5c)
Step-by-step explanation:
Let's build the f(c) function by steps.
There are c customers.
John has found that on average, each meal served costs the restaurant $14.56 and takes in $17.12.
So, the costs for the restaurant are negative, and what takes positive.
f(c) =17.12c -14.56c
Now the final part
John has also found that on average, each beverage served costs the restaurant $1.20 and takes in $5.40.
Half of these customers order a beverage, and this is why we multiply by 0.5.
So
f(c) =17.12c -14.56c + 5.40(.5c) - 1.20(.5c)