Solve the Problem $\{ x \mid 32 < x < 40 \}$

Multiple Choice

Solve the problem.
-The revenue achieved by selling x graphing calculators is figured to be x(50 - 0.5x) dollars. The cost of each calculator is $14. How many graphing calculators must be sold to make a profit (revenue - cost) of at least
$630.00?

A) $\{ x \mid 32 < x < 40 \}$
B) $\{ x \mid 30 < x < 42 \}$
C) $\{ \mathrm { x } \mid 39 < \mathrm { x } < 51 \}$
D) $\{ x \mid 31 < x < 41 \}$