A barrel of oil uses 15 kilograms, and the rest is used (2/3), how many kilograms of this barrel of oil are left?
一桶油用去15千克，剩下的是用去的(2/3)，这桶油剩下多少千克？
<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">1 / (2/3)</gadget>
<output>3/2 = around 1.5</output>

<gadget id="calculator">1 + (3/2)</gadget>
<output>5/2 = around 2.5</output>

<gadget id="calculator">15 / (5/2)</gadget>
<output>6</output>

<result>6</result>