Uncle Zhang raised 90 chickens, 6 more than three times the number of ducks. How many ducks did Uncle Zhang raise?
张大爷家养鸡90只，比鸭的只数的3倍多6只，张大爷养了多少只鸭？
<gadget id="calculator">90 - 6</gadget>
<output>84</output>

<gadget id="calculator">84 / 3</gadget>
<output>28</output>

<result>28</result>