A and B are running a 100-meter race. When A reaches the finish line, B is 20 meters behind A. If the respective speeds of the two remain the same, in order for A and B to reach the finish line at the same time, A's starting line should be behind the original starting line. How many meters to move
甲、乙两人进行百米赛跑，当甲到达终点时，乙在甲后20米；如两人各自的速度不变，要使甲、乙两人同时到达终点，甲的起跑线应比原来后移多少米多少
<gadget id="calculator">100 / 80</gadget>
<output>5/4 = around 1.25</output>

<gadget id="calculator">(5/4) * 100</gadget>
<output>125</output>

<gadget id="calculator">125 - 100</gadget>
<output>25</output>

<result>25</result>