math HELP PLEASE
posted by Angelina .
Ravi is putting up a fence in his backyard. He builds 3 units the first day, 7 units the second day and 11 units the third day. If he continues this pattern, how many days will it take him to finish the 55 unit fence?
Each day he puts up 4 more units than the day before.
By the third day he's put up 21 units.
4th day = 15 units = total 36 units
5th day = 19 units = total = 55 units