There are 120 peach trees. 2 A pear tree is 1.5 times that of an apple tree. 3 There are 210 peach trees and pear trees. According to the conditions provided above, please formulate the equation to find the tree of the apple tree.
1桃树有120棵．2梨树棵树是苹果树的1.5倍．3桃树与梨树共210棵．根据上面提供的条件，请你列方程求出苹果树的棵树．
<gadget id="calculator">210 - 120</gadget>
<output>90</output>

<gadget id="calculator">90 / 1.5</gadget>
<output>60</output>

<result>60</result>