A fruit shop buys apples, oranges and pears. There are more apples than oranges (1/4), and apples are equivalent to pears (7/8). It is known that pears are 50 kg heavier than apples. How many kilograms are you buying oranges? ?
某水果店买进苹果、桔子和梨三种水果，苹果比桔子多(1/4)，苹果相当于梨的(7/8)，已知梨比苹果重50千克，问买进桔子多少千克？
<gadget id="calculator">7 / 8</gadget>
<output>7/8 = around 0.875</output>

<gadget id="calculator">1 - (7/8)</gadget>
<output>1/8 = around 0.125</output>

<gadget id="calculator">50 / (1/8)</gadget>
<output>400</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 + (1/4)</gadget>
<output>5/4 = around 1.25</output>

<gadget id="calculator">(7/8) / (5/4)</gadget>
<output>7/10 = around 0.7</output>

<gadget id="calculator">400 * (7/10)</gadget>
<output>280</output>

<result>280</result>