There are 5 barrels of oil with the same weight. If 15 kg is taken from each barrel, the weight of the remaining oil in the 5 barrels is exactly equal to the weight of the original 2 barrels. How many kilograms does a barrel of oil weigh?
有5桶油重量相等，如果从每只桶里取出15千克，则5只桶里所剩下油的重量正好等于原来2桶油的重量．原来每桶油重多少千克？
<gadget id="calculator">5 - 2</gadget>
<output>3</output>

<gadget id="calculator">5 / 3</gadget>
<output>5/3 = around 1.666667</output>

<gadget id="calculator">15 * (5/3)</gadget>
<output>25</output>

<result>25</result>