The students wanted to plant 65 trees, but they actually planted 28 trees a day, after 2 days of planting. How many are left unplanted?
同学们要种65棵树，实际每天种了28棵，种了2天后．还剩下多少棵没种？
<gadget id="calculator">28 * 2</gadget>
<output>56</output>

<gadget id="calculator">65 - 56</gadget>
<output>9</output>

<result>9</result>