Jean and Mark are going to fill a pool with 2 different sized hoses. Jean can fill the pool in 4 hours, while Mark can complete it in 6 hours. Their supervisor thinks that the job will take 5 hours to complete if they work together. Explain each step in solving this equation, and determine if the supervisor is correct or not.
+312 1/6 + 1/5 = 11/30
30/11 doesn't equal 5 so thee supervisor is wrong. 
