4/5 r=-7 I dont undrstand

What is the value of x in the this question ?

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.

Which equation can be used to measure the density of water in a spherical water tank? let w represent the number of water particles within the region.