The fruit shop shipped 170 boxes of apples, 20 boxes more than three times the number of bananas. How many boxes of bananas were shipped?
水果店运来苹果170箱，比香蕉的3倍多20箱，运来香蕉多少箱？
<gadget id="calculator">170 - 20</gadget>
<output>150</output>

<gadget id="calculator">150 / 3</gadget>
<output>50</output>

<result>50</result>