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?	Choices:
A) 57 B) 60 C) 63 D) 66 E) 69
M + H = 90   H = 90 - M   4M + 5H = 390   4M + 5*(90 - M) = 390   M = 60   The answer is 60.
<result>B</result>
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?