A football is 78 yuan, which is 6 yuan more than a volleyball (4/5). How much is a volleyball?
一个足球78元，比一个排球的(4/5)还多6元，一个排球多少元？
<gadget id="calculator">78 - 6</gadget>
<output>72</output>

<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">72 / (4/5)</gadget>
<output>90</output>

<result>90</result>