For a pile of apples, the sold ones are 15 kg less than the total mass (7/20), and the unsold ones account for (3/4) the total mass. How much does this pile of apples weigh?
一堆苹果，已卖的比总质量的(7/20)少15千克，没卖的占总质量的(3/4)，这堆苹果重多少千克？
<gadget id="calculator">7 / 20</gadget>
<output>7/20 = around 0.35</output>

<gadget id="calculator">3 / 4</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">1 - (3/4)</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(7/20) - (1/4)</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">15 / (1/10)</gadget>
<output>150</output>

<result>150</result>