Xingqing School plans to distribute the tree planting task to the fifth and sixth grade students at a ratio of 3:5. The actual number of trees planted by the sixth grade students accounted for 75% of the total number of trees planted, and the sixth grade students planted 20 more trees than planned. How many trees did the school plan to plant?
兴庆学校计划把植树任务按3：5分给五、六年级的学生．六年级的学生实际植树的棵数占总植树棵数的75%，六年级的学生比计划多植了20棵树．学校原计划植树多少棵？
<gadget id="calculator">75 / 100</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">5 + 3</gadget>
<output>8</output>

<gadget id="calculator">5 / 8</gadget>
<output>5/8 = around 0.625</output>

<gadget id="calculator">(3/4) - (5/8)</gadget>
<output>1/8 = around 0.125</output>

<gadget id="calculator">20 / (1/8)</gadget>
<output>160</output>

<result>160</result>