Problem Solving

A certain NYC taxi driver has decided to start charging a rate of r cents per person per mile. How much, in dollars, would it cost 3 people to travel x miles if he decides to give them a 50% discount?

I think there are two answers to this question
3xr/2
and
3xr /200

it depends if you take 10 cents or .10 cents. The mgmat gives the second as the correct answer but the first one also works.

The only way that the sec choice could only work if we assume that r cents as eg 10 and if is said r is .dollars then a would work. Am I thinking correct.

Thanks
Khurram



We can solve this as a VIC (Variable In answer Choices) and plug in values for x and r.
r
cents per person per mile
10

x
# of miles
20


Since there are 3 people, the taxi driver will charge them 30 cents per mile.
Since they want to travel 20 miles, the total charge (no discount) would be (30)(20) = 600.
With a 50% discount, the total charge will be 300 cents or 3 dollars.

If we plug r = 10 and x = 20 into the answer choices, the only answer that yields 3 dollars is D.

The correct answer is D.