Answer:
C. $25
Explanation:
It is asking how much a flat charge for delivery is. The question explains that the formula represents the cost for a load of bricks, including delivery charge.
0.42b represents 42 cents per brick that gets delivered. No matter how many bricks, (whatever value we plug in for b), there will still be the 25 added to it, so that 25 must be the delivery charge.