Xiaohong goes to the stationery store and buys a football, a volleyball, a basketball, and a pair of badminton rackets. The unit price of basketball is 78 yuan, the unit price of volleyball is 98 yuan, and the unit price of badminton racket is 58 yuan. The unit price of football is lower than that of volleyball, basketball, football and badminton racket The average unit price of these four items is 9 yuan more, what is the unit price of football?
小红去文具店买了一个足球，一个排球、一个篮球、一副羽毛球拍，其中篮球单价78元，排球单价98元，羽毛球拍单价58元，足球的单价比排球、篮球、足球和羽毛球拍这四件商品的平均单价还多9元，求足球单价？
<gadget id="calculator">78 / 4</gadget>
<output>39/2 = around 19.5</output>

<gadget id="calculator">58 / 4</gadget>
<output>29/2 = around 14.5</output>

<gadget id="calculator">98 / 4</gadget>
<output>49/2 = around 24.5</output>

<gadget id="calculator">(39/2) + (29/2) + (49/2) + 9</gadget>
<output>135/2 = around 67.5</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 - (1/4)</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">(135/2) / (3/4)</gadget>
<output>90</output>

<result>90</result>