At the park, Dimitri saw families riding bicycles and tricycles. Bicycles have two wheels and tricycles have three wheels.  6 adults were riding bicycles and 15 children were riding tricycles.   How many wheels did Dimitri see at the park?
Dimitri saw 2 x 6 = 
<gadget id="calculator">2*6</gadget>
<output>12</output>
12 wheels on the bicycles.
He saw 15 x 3 = 
<gadget id="calculator">15*3</gadget>
<output>45</output>
45 wheels on the tricycles.
He saw a total of 12 + 45 = 
<gadget id="calculator">12+45</gadget>
<output>57</output>
57 wheels.

<result>57</result>