In physical education class, Xiao Dingding stood at the starting point of the 100-meter runway, and Xiaopang stood 10 meters in front of him. The two started running in the same direction at the same time. Xiao Dingding ran an average of 5 meters per second, and Xiaopang ran an average of 4.5 meters per second. ． How many seconds did Ding Ding catch up with Fatty?
体育课上，小丁丁站在百米跑道的起点处，小胖站在他前面的10米处，两人同时同向起跑，小丁丁平均每秒跑5米，小胖平均每秒跑4.5米．经过几秒小丁丁追上小胖？
<gadget id="calculator">5 - 4.5</gadget>
<output>0.5</output>

<gadget id="calculator">10 / 0.5</gadget>
<output>20</output>

<result>20</result>