On Friday, Hank opened his used-bicycle store with a stock of bicycles, all fixed-up and ready to ride. Over the course of the day, he sold 10 bicycles and bought an additional 15 to fix up. On Saturday, he sold 12 bicycles and bought 8 more. And on Sunday, he sold 9 bicycles and bought 11 more. What was the net increase in the number of bicycles in stock in Hank's store over the three days?
He sold 10+12+9=
<gadget id="calculator">10+12+9</gadget>
<output>31</output>
31 bicycles.
He bought 15+8+11=
<gadget id="calculator">15+8+11</gadget>
<output>34</output>
34 bicycles.
He now has 34-31=
<gadget id="calculator">34-31</gadget>
<output>3</output>
3 more than at Friday's opening.

<result>3</result>