To rent a tractor, it costs a total of x dollars for the first 24 hour

These kinds of questions (Variables in the Answer Choices - VIACs) can be answered algebraically or using the INPUT-OUTPUT approach.
The other posters above have solved the question algebraically, so let's use the INPUT-OUTPUT approach.

First, choose values for x and y
Let's say x = 4 and y = 3

In other words, to rent a tractor, it costs a total of 4 dollars for the first 24 hours, plus 3 dollars per hour for each hour in excess of 24 hours. Which of the following represents the cost, in dollars, to rent a tractor for 36 hours?

TOTAL cost = 4 dollars (for the first time for hours) + (12)(3 dollars) (for each of the 12 hours after the first 24 hours)
= 4 + 36
= 40 (dollars)

So, when x = 4 and y = 3, the answer to the question is 40 (dollars)
In other words, when we INPUT x = 4 and y = 3, the OUTPUT is 40

We'll now take each answer choice and plug-in x = 4 and y = 3.
The correct answer choice will be the one that evaluates to be 40

(A) 4 + 12(3) = 40 Great!
(B) 4 + 36(3) = 112. No good. We need an output of 40
(C) 12(4) + 3 = 51. No good. We need an output of 40
(D) 24(4) + 12(3) = 132. No good. We need an output of 40
(E) 24(4) + 36(3) = 204. No good. We need an output of 40

Answer: A

Cheers,
Brent

Cost for first 24 hours = $ x… x is not per hour cost
Cost for next 36 hours = 36*y…y is per hour cost

Total cost = \(x + 36y\)

Answer: Option B

To rent a tractor for 36 hours:
x dollars for the first 24 hours
-----PLUS-------------------------
y dollars per hour for each hours = 36y
--> x + 36y

Answer (B).

"... per hour for each hour in excess of 24 hours ..."

Answer: X + (36 -24) Y = X + 12 Y

The cost to rent the tractor for 36 hours is:

x + y(36 - 24) = x + 12y

Answer: A
_________________

Given:
1. Total hours (T): 36
2. $X for 1st 24 hours and $Y additional for every hour after 1st 24 hrs

Therefore, total cost: X + ( T-24)*Y
=> X+ (36-24)*Y
=> X + 12Y (Option A)

In excess of hours means only 12 hours count for $y per hour. Hence
x + 12y

Answer E.
_________________

X Dollars for the first 24 hours. So, the cost to rent a tractor for the first 24 out of 36 is X.
Remaining hours = 12. Cost for these = Y/Hour.

There total cost = X+12Y.
Option A.

A- x + 12y
x - cost for first 24 hours and y - cost per hour

The cost for first 24 hours is $x

Total rent time = 36 hours

Total amount spent for 36 hours = cost for first 24 hours + (cost for each additional hour)(36 - 24)
= x + 12y
Therefore answer is Option A

For first 24 Hours cost is x
For next 12 Hours cost is 12y

So, Total cost is x + 12y, Answer must be (A)
_________________

[b]SOLUTION:[/b]

For the first 24 hours rent, the FIXED cost = x dollars

Hence the remaining 36-24 = 12 hours are billed @ y dollars/hour

=>VARIABLE Cost incurred = 12y dollar

=> Total cost incurred = Fixed Cost + Variable Cost

(x + 12y ) (OPTION A)

Hope this helps
Devmitra Sen(Math)

_________________

Answer: Option A

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Rent for 36 horse = Rent for first 24 hours + rent for 12 hours = x+12y

Hence Answer is A

Total cost = Cost for the first 24 hours + Cost for additional hours
Total cost = x + (y*12)

Answer is A