stumped on a discrete quantitative question from Barron's

[patrakakali79]

Evan has 4 times as many books as David and 5 times as many as Jason.If Jason has more than 40 books , what is the least no. of books Evan could have?

A) 200
B) 205
C) 210
D) 220
E) 240

The way I did:
Let E represent the no. of books Evan has,J the no. of books Jason has and D the no. of books David has.

E= 4D => D = E/4
E = 5J => J = E/5
J > 40 => E/5 > 40 => E > 200

Among the options 205 comes after 200
Ans : B

But correct answer (D) - 220

Please help.....

[tommywallach]

Hey Patra,

You're right, but it's a secretly tricky question. Ask yourself: "Why did they tell me about David?" Remember, the GRE doesn't give you information about something if you don't need it, so there must be a reason. It turns out that Evan's number of books needs to be divisible by 4, because we know he has exactly 4 times as many books as David has. So the answer needs to be the first thing that is bigger than 20 but ALSO divisible by 4. That's 220.

-t