A company has two models of computers, model M and model N. Operating at a constant rate, a model M computer can complete a certain task in 36 minutes and a model N computer can complete the same task in 18 minutes. If the company used the same number of each model of computer to complete the task in 1 minute, how many model M computers were used?  Answers
A) 12 B) 11 C) 10 D) 9 E) 8

Rationale: "let ' s say 1 work is processing 36 gb of data . model m : 1 gb per min model n : 2 gb per min working together , 1 m and 1 n = 3 gb per min so , 12 times as many computers would work at 36 gb per min . so no . of m = 12 answer is a"
Answer: A