A man bring 2 cats to his home to eliminate all the mice. They do a half of the work in 5 days, then the man brings 3 more cats. If they hunt at the same rate, how many days will take to hunt all the mice, since the first day?
Choose the correct choice from the following answers
A) 7 days
B) 8 days
C) 9 days
D) 10 days
E) 11 days

Rationale: we have that : 2 cats - - - - - 5 days , ( 2 + 3 ) c - - - - - x d , that is : ( x d / 2 c ) = ( 5 d / 5 p ) , then : x d = ( 5 d / 5 c ) 2 c = 2 d . is to say , the 5 cats hunt the same quantity in 2 days ; as it is only 1 / 2 of the work , all the mice would be hunt in : m = 5 d + 2 d = 7 days . answer a .
Answer: A