The students planted trees. The third grade planted 150 trees, and the fourth grade planted 25 fewer trees than the third grade. The fifth grade planted 100 fewer trees than the third and fourth grades. How many trees were planted in the third, fourth, and fifth grades?
同学们栽树，三年级栽了150棵，四年级栽的比三年级的2倍少25棵．五年级栽的比三、四年级栽的总数少100棵．三、四、五年级一共栽了多少棵？
<gadget id="calculator">150 * 2</gadget>
<output>300</output>

<gadget id="calculator">300 - 25</gadget>
<output>275</output>

<gadget id="calculator">275 - 100</gadget>
<output>175</output>

<gadget id="calculator">150 + 175</gadget>
<output>325</output>

<gadget id="calculator">150 + 275 + 325</gadget>
<output>750</output>

<result>750</result>