On Sunday, Xiao Ming's father caught a crucian carp and a carp in the river, which weighed 2 kilograms in total, and the carp weighed (5/4) kilograms. How much lighter is the crucian carp than the carp?
星期天，小明的爸爸在河里钓了一条鲫鱼和一条鲤鱼，一共重2千克，其中鲤鱼重(5/4)千克，鲫鱼比鲤鱼轻多少千克？
<gadget id="calculator">5 / 4</gadget>
<output>5/4 = around 1.25</output>

<gadget id="calculator">2 - (5/4)</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">(5/4) - (3/4)</gadget>
<output>1/2 = around 0.5</output>

<result>1/2 = around 0.5</result>