The sixth grade students planted 275 trees, which is 20 more than the number of trees planted by the fifth grade. How many trees are planted in the fifth grade?
六年级同学植树275棵，比五年级植树棵数的1.5倍还多20棵，五年级植树多少棵？
<gadget id="calculator">275 - 20</gadget>
<output>255</output>

<gadget id="calculator">255 / 1.5</gadget>
<output>170</output>

<result>170</result>