I think the answer is y=1/4x+2 :)
we have

This is a mixed number
we know that
A mixed number is a combination of a whole number and a fraction.
So
is equal to

where
is the whole number
is the fraction

therefore
the answer is

Part A: Chose some value for x, that means any amount of books to print for example 100 books, so x=100
Replace x=100 in C(x) and solve:
C(100)=3.5*100+1200=1550
Part B: Replace C(x) by 1900 and solve for x from the given equation:
1900=3.5x+1200
3.5x=1900-1200
x=700/3.5= 200
Part C: the statement C(20)=1270 means that 1270 is the cost for printing 20 books.
Part E: C(40.5)=1341.75 I think this statement is incorrect given the context because x means number of books to print so this value must be an integer number.
Given that for each <span>$2 increase in price, the demand is less and 4 fewer cars are rented.
Let x be the number of $2 increases in price, then the revenue from renting cars is given by

.
Also, given that f</span><span>or each car that is rented, there are routine maintenance costs of $5 per day, then the total cost of renting cars is given by

Profit is given by revenue - cost.
Thus, the profit from renting cars is given by
</span><span>

For maximum profit, the differentiation of the profit function equals zero.
i.e.
</span><span>

The price of renting a car is given by 48 + 2x = 48 + 2(8) = 48 + 16 = 64.
Therefore, the </span><span>rental charge will maximize profit is $64.</span>