Every 10 seconds, there is a car collision, and every 20 seconds there is a big crash. How many accidents overall will happen in 4 minutes?
1 minute is 60 seconds, so 4 minutes is 4 * 60 = 
<gadget id="calculator">4*60</gadget>
<output>240</output>
240 seconds.
During this time there would be 240 / 20 = 
<gadget id="calculator">240/20</gadget>
<output>12</output>
12 big crashes.
And also 240 / 10 = 
<gadget id="calculator">240/10</gadget>
<output>24</output>
24 car collisions.
So in total during 4 minutes there would be 12 + 24 = 
<gadget id="calculator">12+24</gadget>
<output>36</output>
36 accidents.

<result>36</result>