One approach is to ASSIGN SOME "NICE" VALUES

Let's say the price per ticket = $1
So, the TOTAL cost (i.e., without a discount) for Abby, Brandon, Cedric, and Deirdre will be $4

The total price of the tickets with the group discount is the same as the total price of the tickets without the group discount
When Kim comes too, the TOTAL discounted price will be $4

Of course, if tickets are $1 each, then the TOTAL cost (without discount) for the five people SHOULD be $5

So, what's the discount (expressed as a percent)?
The discount = (100)(5 - 4)/5
= 100/5
= 20%

Answer:
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Let A,B,C and D individual tickets be X and total tickets is 4X..

Now with Kelly they get a discount , total tickets here is 5x.

We are told that group discount is same as total price without discount..

When we need to solve 5X till we get 4X..

Take options..5X - 5%(5X) = 5x - (0.05)(5X) = 5x - 0.25X = 4.75X...not same as 4X..
(B) 5X - 10% of 5x => 5x - (0.1)(5x) = 4.5X, which is again not equal to 4x. So, this is not the correct option.
(C) 5X - 20% of 5x => 5x - (0.2)(5x) = 4X, this is same as 4X...no need to do other options..

IMO option C is correct answer...

OA please...will correct if I missed anything..

We can create the equation in which p = the regular price and n = the percent of the discount:

5p(1 - n/100) = 4p

(100 - n)/100 = 4/5

5(100 - n) = 400

500 - 5n = 400

100 = 5n

n = 20 percent

Answer: C
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Tried solving this question by taking a number.

Lets say the cost of 4 tickets =100 Rs.
i.e. each ticket will cost 25 Rs.

Now after applying the group discount still the cost of tickets remain same but now for 5 folks. Hence each ticket is of 20 Rs.

Now, x% * 25= 20
x = 20*100/25 = 80%

Hence the discount is 100-80= 20%

Answer is C.

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