students in class 31 plant trees. If each person plants 4 trees and there are 3 trees left, how many trees will they plant in total?
三1班9名同学植树，如果每人植4棵，还剩3棵，他们一共要植树多少棵？
<gadget id="calculator">9 * 4</gadget>
<output>36</output>

<gadget id="calculator">36 + 3</gadget>
<output>39</output>

<result>39</result>