Two persons work together at the local aquarium. It takes the first person 120 minutes to clean the jellyfish tanks. Since the second person is new to the job, it takes him longer to perform the same task. When working together, they can perform the task in 70 minutes. How long does it take the second person to do the task by himself?
+36916 1st person rate = 1 tank / 120 m
2nd person rate = 1 tank / x m
1 tank / ( 1 tank/120m + 1tank/xm) = 70 m
1 / (1/120 + 1/x) = 70
1 = 70 ( 1/120 + 1/x)
1 - 70/120 = 70/x
x= 168 m
