Use a balance to weigh a piece of mooncake, put a piece of mooncake in the left pan of the balance, put (3/4) piece of mooncake and 20 grams of weight in the right pan of the balance, the balance is flat, how many grams does this mooncake weigh?
用天平称一块月饼，天平的左盘里放一块月饼，天平的右盘里放(3/4)块月饼和20克砝码，天平是平的，这块月饼有多少克？
<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">20 / (1/4)</gadget>
<output>80</output>

<result>80</result>