At a school, 40% of the students receive a free lunch. These lunches are paid for by making sure the price paid by the paying students is enough to cover everyone's meal. If it costs $210 to feed 50 students, how much do the paying students pay for lunch?
60% of the students pay for the lunch because 100 - 40 = 
<gadget id="calculator">100-40</gadget>
<output>60</output>
60
30 students pay for lunch because 50 x .6 = 
<gadget id="calculator">50*.6</gadget>
<output>30</output>
30.
These students pay $7 for their lunch because 210 / 30 =
<gadget id="calculator">210/30</gadget>
<output>7</output>
7.

<result>7</result>