Great question: Realtors based on their broker agreement can vary, however general rule of thumb :
Listing broker agent 3% of sales price - broker can takes a % based on realtors contract
Buyers broker agent 3 % of sales price - broker can takes a % based on realtors contract
Listing agreement with seller can vary what the listing broker and buyer broker can earn based on seller specifications.
Monique is correct regarding after an real estate agent receive the % from broker they have to cover their own expenses from car, insurance, gas, maintenance phones, computers, websites, office desk fees, website expenses, pass keys, signs, lock boxes, office supplies, state regulated educational classes, realtor board fees, much much more.