Average of money that group of 4 friends pay for rent each month is $800.After one persons rent is increased by 20% the new mean is $870.What was original rent of friend whose rent is increased?  Choose the correct choice from the following options
A) 800  B) 1400  C) 1000  D) 1100  E) 1200

Rationale: "0.2 x = 4 ( 870 - 800 ) 0.2 x = 280 x = 1400 answer b"
Answer: B