Machine A and machine B are each used to manufacture 440 sprockets. It takes machine A 10 hours longer to produce 440 sprockets than machine B. Machine B produces 10 percent more sprockets per hour than machine A. How many sprockets per hour does machine A produces?	Choose the correct choice from the following answers:
A) 5
B) 6
C) 4
D) 3
E) 2

Rationale: "machine b : takes x hours to produce 440 sprockets machine a : takes ( x + 10 ) hours to produce 440 sprockets machine b : in 1 hour , b makes 440 / x sprockets machine a : in 1 hour , a makes 440 / ( x + 10 ) sprockets equating : 1.1 ( 440 / ( x + 10 ) ) = 440 / x 484 / ( x + 10 ) = 440 / x 484 x = 440 x + 4400 44 x = 4400 x = 100 a makes 440 / ( 110 ) = 4 sprockets per hour answer : c"
Answer: C