We bought a total of 90 books at the store. Math books cost $4 and history books cost $5. The total price was $390. How many math books did we buy?	Choose the correct choice from the following choices:
A) 57 B) 60 C) 63 D) 66 E) 69

Rationale: "m + h = 90 h = 90 - m 4 m + 5 h = 390 4 m + 5 * ( 90 - m ) = 390 m = 60 the answer is b ."
Answer: B