The express train departs from point A and the slow train departs from point B at the same time, and they run towards each other. After 4 hours, they meet. After meeting, the two cars continue to move forward at the original speed. After another 5 hours, the slow train still has 20 kilometers to reach point A. The express train has surpassed B by 120 kilometers. How many miles is the distance between A and B?
快车从A地，慢车从B地同时出发，相向而行，经过4小时相遇，相遇后两车仍按原来速度继续前进，又经过5小时，这时慢车还有20千米就到达A地，快车已超过B地120千米．A、B两地的路程是多少千米？
<gadget id="calculator">120 - 20</gadget>
<output>100</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(1/4) * 5</gadget>
<output>5/4 = around 1.25</output>

<gadget id="calculator">(5/4) - 1</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">100 / (1/4)</gadget>
<output>400</output>

<result>400</result>