1. Ana was washing dishes at the end of her shift at a restaurant. She washed 30 plates from 7:30 to 7:35. When she finishes washing all the plates, her shift will end.
(a) If she started washing plates at 7:15 and ended at 7:38, estimate how many plates she washed in total. Explain your reasoning.
(b) Write an equation to represent how many plates Ana has left to wash at a particular time after her start at 7:15. Explain your reasoning.