There was a series of two successive discounts of y% on the price of L

Hello,

Greetings for the day!

This is a simple question which can be solved by assuming $100 as the price of the laptop and working backwards to obtain the final price of the laptop as $64.
Since we have to calculate the value of ‘y’, the options should naturally reflect this.

Clearly, options D and E cannot be the answers.

1 discount of 82% will take the price of the laptop much below $64, then where is the question of applying another 82% and getting $64.

A similar thing happens with option D. 36% of 100 is 36. Hence, after the first discount itself, the price reduces to $64. Now, if we apply another 36% discount, the price will not stay at $64, right?

So, options D and E are out of our way.

Now, out of the remaining options, let us pick 20%, because, this is clearly an easy number to deal with, considering the price of the laptop we have assumed.
When we apply the first discount of 20%, 100 becomes 80. When we apply the second discount of 20%, 80 becomes 64. This is clearly what we wanted.

Hence, the answer option is B.

The best approach for answering such questions is a combination of two approaches – eliminate the choices which do not make any sense and subsequently back solve using the answer options provided.

When you are picking options using which to back solve, pick numbers which are easy to deal with. Remember, it’s not a challenge to pick the most difficult option and then work backwards.

Post script: Alternatively, you can use the formula for successive discounts which is [ -a –b + ab/100]%

Hope this helps!
Cheers.