There were 100 people in attendance at the school dance.  Ten percent of the attendees were school faculty and staff.  Of the remaining attendees, two-thirds were girls.  How many boys attended the school dance?
Of 100 people in attendance at the school dance, 10% were school faculty and staff, or a total of 0.1*100=
<gadget id="calculator">100*0.1</gadget>
<output>10</output>
10 people.
This leaves 100-10=
<gadget id="calculator">100-10</gadget>
<output>90</output>
90 students in attendance.
Of the remaining attendees, two-thirds were girls, or (2/3)*90=
<gadget id="calculator">(2/3)*90</gadget>
<output>60</output>
60 attendees were girls.
Thus, the remaining 90-60=
<gadget id="calculator">90-60</gadget>
<output>30</output>
30 students were boys who attended the school dance.

<result>30</result>