Humans of earth! I REALLY DO NOT UNDERSTAND THIS QUESTION PLEASE HELP ASAP! I AM TRYING TO FIGURE THIS OUT BUT I DO NOT GET IT.... SORRY TO BOTHER YOU.....Expand the expression -5 (3b-7)

I WILL GIVE BRAINLIEST IF I SEE GOOD EXPLANATION'S AND IF I CAN. 5 TO 10 POINTS GIVEN ON THIS QUESTION