If $120 invested at a certain rate of simple interest amounts to $180 at the end of 3 years,How much will $150 amount to at the same rate of interest in 6 years?  Choose the correct choice from the following.
A) $ 190	B) $ 180	C) $ 200	D) $ 240	E) $ 300

Rationale: "120 amounts to 180 in 3 years . i . e ( principal + interest ) on 120 in 3 years = 180 120 + 120 * ( r / 100 ) * ( 3 ) = 140 = > r = 50 / 3 150 in 6 years = principal + interest = 300 answer is e ."
Answer: E