% problem

[Nycgrl]

MONTHLY KILOWATT-HOURS
500 1,000 1,500 2,000
Present $24.00 $41.00 $57.00 $73.00
Proposed $26.00 $45.00 $62.00 $79.00

12. The table above shows present rates and proposed rates for electricity for residential customers. For which of the monthly kilowatt-hours shown would the proposed rate be the greatest percent increase over the present rate?
(A) 500
(B) 1,000
(C) 1,500
(D) 2,000
(E) Each of the percent increases is the same.

[somail]

The most important formula for this question is ((change)/original)*100 = %change

Using the first value 500KW

500X24.00= $12,000
500x26.00= $13,000

13k-12k = $1,000 ($1,000/$12,000)*100= 8.33% change.

Use the same process for the remaining values.

[Nycgrl]

Is there ant shor method to do it

[Sunny22uk]

As Somail said, the formula is ((change)/original)*100 = %change
Instead of multiplying MONTHLY KILOWATT-HOURS,We can rewrite the solution as:-
500(26-25)/ (500*24) x 100 i.e. 1/24 * 100
As seen in this equation, there is no need to multiply MONTHLY KILOWATT-HOURS, the rest of the equations will be easy to solve.

Hope this helps.
Cheers