Justin needs to collect one flower for each classmate that is in his 2nd-grade class. It takes him on average 10 minutes to find a flower he likes. He has been gathering for 2 hours. Assuming he has lost 3 of the flowers he initially gathered, how many more minutes does he need to look if he has 30 classmates?
If he gathers for 2 hours, the number of minutes gathering is 2 * 60 minutes per hour = 
<gadget id="calculator">2*60</gadget>
<output>120</output>
120 minutes of gathering flowers.
Gathering for 120 minutes / 10 minutes per flower = 
<gadget id="calculator">120/10</gadget>
<output>12</output>
12 flowers gathered.
If he gathers 12 flowers initially but lost 3, he has 12-3 = 
<gadget id="calculator">12-3</gadget>
<output>9</output>
9 flowers gathered and kept.
Since he has 30 classmates total and has 9 flowers, he needs to gather 30-9=
<gadget id="calculator">30-9</gadget>
<output>21</output>
21 more flowers.
Assuming it takes 10 minutes per flower, it will take him 10 * 21 = 
<gadget id="calculator">10*21</gadget>
<output>210</output>
210 minutes to gather the remaining 21 flowers needed.

<result>210</result>