Company X provides bottled water to its employees in 5 liter bottles, $5 each. At least how many 5L bottles must Company X buy monthly, so that new contract with $40 fixed monthly rate and $2 for 20L bottle each paid off? (Assume that no other costs apply) Answers.
A) 4	B) 9	C) 12	D) 20	E) 25

Rationale: let the no . of 5 liter bottles be x , so the no . of 20 l bottles will be x / 4 ( to equate the vol . ) since the total cost will be equal , 5 x = 40 + 2 * x / 4 so x = 8.88 or 9 . answer is ( b ) .
Answer: B