A barrel of oil is 5 kilograms, pour out 1/2 of the oil for the first time, and pour out 1 kilogram for the second time, how many kilograms of oil are left in the barrel.
一桶油5千克，第一次倒出油的(1/2)，第二次倒出1千克，桶内还剩油多少千克．
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

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

<gadget id="calculator">5 - (5/2) - 1</gadget>
<output>3/2 = around 1.5</output>

<result>3/2 = around 1.5</result>