The answer is

B! I agree with ggarr

I tried this using various numbers, $8 & $10, $9 and $11.25, etc.

Then I used a variety of different hours/week.

If you figure $8 before raise at 30 hrs/wk=$240/wk

Then take the weekly wage $240 and divide it by the new hourly wage ($8*1.25=$10) and you have

240/10=24

Then use the comparison

24/30=.8, then 1-.8=.2=

20% reduce in workload.

I think it's

B
Using briks123's example, you have to remember it's a

decrease in workload, not an increase, so you take 16/20=.8, and subtract that from 1 to give you .2 or

20%,

not 20/16. (BTW 20/16 gives you how much she would have to

increase her workload to maintain the same income level after a

cut in pay), but you were on the right track!

However, if anyone knows a way to figure this out using a special rule,

please let me know! I need to work on speed and pacing, so I know I won't have time to plug in experimental numbers during the real GMAT!