Zhang Weidong plans to complete 20 math problems on the weekend, and he has already completed 16. How close is it to finish?
张卫东计划在周末完成20道数学题，已经完成16道，还差几分之几就可以完成？
<gadget id="calculator">16 / 20</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">1 - (4/5)</gadget>
<output>1/5 = around 0.2</output>

<result>1/5 = around 0.2</result>