Miss Molly surveyed her class of 30 students about their favorite color. Half of the class answered green, one-third of the girls answered pink, and the rest of the class answered yellow. If there are 18 girls in the class, how many students like yellow best?
30/2 = 
<gadget id="calculator">30/2</gadget>
<output>15</output>
15 students answered green.
18/3 = 
<gadget id="calculator">18/3</gadget>
<output>6</output>
6 girls answered pink.
So, 15 + 6 = 
<gadget id="calculator">15+6</gadget>
<output>21</output>
21 students answered either green or pink.
Therefore, 30 - 21 = 
<gadget id="calculator">30-21</gadget>
<output>9</output>
9 answered yellow.

<result>9</result>