It takes a dog groomer 10 minutes to dry a short-haired dog like a beagle.  It takes him twice as long to dry a full-haired, fluffy dog like a german shepherd.  One morning, he has 6 short-haired dogs to dry and 9 full-haired dogs to dry.  How many hours does it take him to dry all of the dogs?
It takes 10 minutes to dry the coat of a short-haired dog and twice as long for a full haired dog so they take 10*2 = 
<gadget id="calculator">10*2</gadget>
<output>20</output>
20 minutes to dry.
He had 6 short hair dogs and they took 10 minutes to dry each so they took 6*10= 
<gadget id="calculator">6*10</gadget>
<output>60</output>
60 minutes to dry.
He had 9 full haired dogs that took 20 minutes to dry each so they took 9*20 = 
<gadget id="calculator">9*20</gadget>
<output>180</output>
180 minutes to dry.
Together is takes him 60+180 = 
<gadget id="calculator">60+180</gadget>
<output>240</output>
240 minutes to dry all of the dogs
60 minutes are in 1 hour and he spends 240 minutes on the dogs so he worked for 240/60 = 
<gadget id="calculator">240/60</gadget>
<output>4</output>
4 hours drying the dogs.

<result>4</result>