The original number of footballs in Hope Primary School is the sum of the number of basketballs and footballs (5/13). This year, when the school starts, 24 more basketballs have been purchased. The number of existing footballs is the sum of the numbers of the two balls (5/17) ． How many footballs do I hope primary schools have?
希望小学原有足球的个数是篮球与足球个数和的(5/13)，今年开学，又购进24个篮球，现有足球个数是两种球个数和的(5/17)．希望小学原有足球多少个．
<gadget id="calculator">17 - 5</gadget>
<output>12</output>

<gadget id="calculator">12 / 5</gadget>
<output>12/5 = around 2.4</output>

<gadget id="calculator">13 - 5</gadget>
<output>8</output>

<gadget id="calculator">8 / 5</gadget>
<output>8/5 = around 1.6</output>

<gadget id="calculator">(12/5) - (8/5)</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">24 / (4/5)</gadget>
<output>30</output>

<result>30</result>