Dad planted 4 pear trees in the open space, and the number of apple trees planted is 7 times that of pear trees. How many apple trees are there?
爸爸在空地上种了4棵梨树，种苹果树棵数是梨树的7倍．苹果树种多少棵．
<gadget id="calculator">4 * 7</gadget>
<output>28</output>

<result>28</result>