The school handed over the tree planting task to three classes. If cut separately, Class A needs 12 days to complete, Class B needs 10 days to complete, and Class C needs 15 days to complete. After the three classes planted together for 3 days, there are still 90 trees left to be planted. How many trees will the school plant in total?
学校把植树任务交给三个班．如果单独裁，甲班需要12天完成，乙班需要10天完成，丙班需要15天完成．三个班合栽了3天后，还剩90棵没栽完，学校共要植树多少棵？
<gadget id="calculator">1 / 12</gadget>
<output>1/12 = around 0.083333</output>

<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">1 / 15</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">(1/12) + (1/10) + (1/15)</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(1/4) * 3</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">1 - (3/4)</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">90 / (1/4)</gadget>
<output>360</output>

<result>360</result>