After a barrel of oil is used up (1/4), exactly 45 kilograms remain. How many kilograms does this barrel of oil weigh?
一桶油用去(1/4)后，正好余下45千克，这桶油重多少千克？
<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">45 / (3/4)</gadget>
<output>60</output>

<result>60</result>