The two biological teams produced 690 butterfly specimens in 15 days. The first group made 20 per day, the second group made how many per day.
两个生物小组15天共制作蝴蝶标本690个．第一组每天制作20个，第二组每天制作多少个．
<gadget id="calculator">690 / 15</gadget>
<output>46</output>

<gadget id="calculator">46 - 20</gadget>
<output>26</output>

<result>26</result>