Question

Sharon makes $1250 per month plus 20% per month plus 15% commission. If they both sold $20000, who made more money that month?

Answer 1

You type "they both ... "    This indicates that there are TWO people involved, not just one.  

"plus 20% per month plus 15% commission" isn't quite clear.  Is that 20% of the base pay ($1,250)?  I assume that the 15% commission is figured on the sales ($20,000)

Please clarify this as much as you can.