The school divides the tree planting task between the fourth and fifth grades at a ratio of 4:5. The fourth grade actually planted 120 trees, exceeding 25% of the original assignment. How many trees were originally planned for the fifth grade?
学校把植树任务按4：5分给四年级和五年级．四年级实际栽了120棵，超过原分配任务的25%，原计划五年级植树多少棵？
<gadget id="calculator">25 / 100</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 + (1/4)</gadget>
<output>5/4 = around 1.25</output>

<gadget id="calculator">120 / (5/4) / 4</gadget>
<output>24</output>

<gadget id="calculator">24 * 5</gadget>
<output>120</output>

<result>120</result>