The older sister and the younger sister walk toward each other from home and school respectively, meet each other in 4 minutes, and then move on. When the older sister takes another 3 minutes to reach the school, how many minutes will it take for the younger sister to reach home?
姐姐和妹妹分别从家和学校两地相向而行，4分钟相遇，然后继续前进，姐姐又用3分钟到达学校时，妹妹还需要多少分钟到达家？
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 / 7</gadget>
<output>1/7 = around 0.142857</output>

<gadget id="calculator">(1/4) - (1/7)</gadget>
<output>3/28 = around 0.107143</output>

<gadget id="calculator">1 / (3/28)</gadget>
<output>28/3 = around 9.333333</output>

<gadget id="calculator">(28/3) - 7</gadget>
<output>7/3 = around 2.333333</output>

<result>7/3 = around 2.333333</result>