Answer:
yards of wire left on the roll = 500 - r(3)
Step-by-step explanation:
9 feet = 3 yards we need to find how much wire is left on the roll after she builds a certain amount of robots. she uses 9 feet or 3 yards per robot so we have to multiply the amount of robots (r) by 3 yards and subtract that from 500 yards or the total amount of wire she has and that gives us the total amount of wire she has left. Hope this helps.