The school held a 100-meter race. Xiao Ming took 15 seconds. Xiao Hua was 3 seconds slower than Xiao Ming. How many seconds did Xiao Hua take?
学校举行100米跑比赛，小明用了15秒，小华比小明慢3秒，小华用了多少秒．
<gadget id="calculator">15 + 3</gadget>
<output>18</output>

<result>18</result>