There are 45 volleyballs and basketballs in the store. Among them, volleyballs account for (3/5) of the total. After selling some volleyballs, volleyballs account for (1/4) of the total. How many volleyballs are sold?
商店有排球和篮球共45只．其中排球占总数的(3/5)，卖出一些排球后，排球占现在总数的(1/4)，卖出排球多少只．
<gadget id="calculator">3 / 5</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">45 * (3/5)</gadget>
<output>27</output>

<gadget id="calculator">45 - 27</gadget>
<output>18</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">18 / (3/4)</gadget>
<output>24</output>

<gadget id="calculator">45 - 24</gadget>
<output>21</output>

<result>21</result>