A store sells pencils for $0.50 each and erasers for $1.00 each. If a student buys a total of 10 items for $6.00, how many pencils did the student buy?
Answer: B. 6
Let x be the number of pencils and y be the number of erasers. The equations are x + y = 10 and 0.5x + y = 6. Solving gives x = 6.