This is applying systems

Troy and his sister Caitlin can earn money by choosing to do chores around the house. Last month, Caitlin earned $5 more than twice what Troy earned. If the sum of their earnings was $80, how much did Caitlin earn last month?

Katie wants to collect over 100 seashells. she already has 34 seashells in her collection. each day, she finds 12 more seashells on the beach. katie can use fractions of days to find seashells. write an inequality to determine the number of days, dd, it will take katie to collect over 100 seashells.