Whats this one? pls

Atriangle with all sides of equal length is a/an triangle. a. right b. scalene c. equilateral d. isosceles

Ian is in training for a national hot dog eating contest on the 4th of july. on his first day of training, he eats 4 hot dogs. each day, he plans to eat 110% of the number of hot dogs he ate the previous day. write an explicit formula that could be used to find the number of hot dogs ian will eat on any particular day.

What is r i 4.5+10r=-6.5 with work pls