I went to People’s Park to visit the chrysanthemum exhibition with my younger brother. The younger brother walked 50 meters per minute. After walking for 10 minutes, the older brother chased the younger brother at a speed of 70 meters per minute. Ask: How many minutes will it take for the older brother to catch up with the younger brother?
和弟弟去人民公园参观菊花展，弟弟每分钟走50米，走了10分钟后，哥哥以每分钟70米的速度去追弟弟，问：经过多少分钟以后哥哥可以追上弟弟？
<gadget id="calculator">70 - 50</gadget>
<output>20</output>

<gadget id="calculator">10 / 20</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">50 * (1/2)</gadget>
<output>25</output>

<result>25</result>