Brian loves watching animal videos online.  He watches a 4-minute video of cats.  He then watches a video twice as long as the cat video involving dogs.  He finishes up his video watching for the day by watching a video on gorillas that's twice as long as the previous two videos combined.  How many minutes does Brian spend watching animal videos?
Brian begins by watching a 4-minute video, and since the second video is twice as long that means the second video is 4*2= 
<gadget id="calculator">4*2</gadget>
<output>8</output>
8 minutes.
The first two videos combined therefore for a 4+8=
<gadget id="calculator">4+8</gadget>
<output>12</output>
12 minute run time.
Since the third video is twice as long as the first two videos put together, that means it is 12*2=
<gadget id="calculator">12*2</gadget>
<output>24</output>
24 minutes in length.
The total length of time spent is therefore 24+12= 
<gadget id="calculator">24+12</gadget>
<output>36</output>
36 minutes.

<result>36</result>