Chunlei Primary School organized students to collect tree species. It was planned to collect 120 kilograms of tree species in 20 days. The actual collection was 1.5 kg more than planned every day. How many days did it actually take to collect this batch of tree species?
春蕾小学组织同学们进行收集树种活动，计划20天收集树种120千克，实际每天比计划多收集1.5千克，收集这批树种实际用了多少天？
<gadget id="calculator">120 / 20</gadget>
<output>6</output>

<gadget id="calculator">6 + 1.5</gadget>
<output>7.5</output>

<gadget id="calculator">120 / 7.5</gadget>
<output>16</output>

<result>16</result>