Grandma Wang brought back 25 baskets of apples and pears. After selling 25% of the apples and 4 baskets of pears yesterday, the remaining baskets of apples and pears were exactly equal. How many baskets of apples did Grandma Wang sell yesterday?
王奶奶进回苹果和梨共25筐，昨天售出苹果的25%和4筐梨后，剩下的苹果和梨的筐数正好相等．王奶奶昨天售出苹果多少筐？
<gadget id="calculator">25 - 4</gadget>
<output>21</output>

<gadget id="calculator">25 / 100</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">1 + (3/4)</gadget>
<output>7/4 = around 1.75</output>

<gadget id="calculator">21 / (7/4)</gadget>
<output>12</output>

<gadget id="calculator">12 * (1/4)</gadget>
<output>3</output>

<result>3</result>