Students in grades five and six planted trees. The number of trees planted in grade five accounted for 40% of the total number of trees. The number of trees planted in grade six accounted for 60% of the total number of trees. Grade six planted 15 more trees than grade five. How many trees.
五六年级同学去植树，五年级植树棵树占总棵树的40%，六年级植树的棵树占总棵树的60%，六年级比五年级多植15棵树，两个年级一共植树多少棵．
<gadget id="calculator">60 / 100</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">(3/5) - (2/5)</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">15 / (1/5)</gadget>
<output>75</output>

<result>75</result>