30% of a barrel of oil is used, which is exactly (3/2) kilograms. How many kilograms of oil are left in this barrel?
一桶油，用去30%，正好是(3/2)千克，这桶油还剩多少千克？
<gadget id="calculator">3 / 2</gadget>
<output>3/2 = around 1.5</output>

<gadget id="calculator">30 / 100</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">(3/2) / (3/10)</gadget>
<output>5</output>

<gadget id="calculator">5 - (3/2)</gadget>
<output>7/2 = around 3.5</output>

<result>7/2 = around 3.5</result>