Two people, A and B, start from a certain point on the ring road at the same time, and walk with their backs. It is known that it takes 48 minutes for A to ride a circle, and they meet 30 minutes after departure. Question: How many minutes does it take B to ride around.
甲、乙二人骑车同时从环形公路的某点出发，背向而行，已知甲骑一圈需48分钟，出发后30分钟两人相遇．问：乙骑一圈需多少分钟．
<gadget id="calculator">1 / 30</gadget>
<output>1/30 = around 0.033333</output>

<gadget id="calculator">1 / 48</gadget>
<output>1/48 = around 0.020833</output>

<gadget id="calculator">(1/30) - (1/48)</gadget>
<output>1/80 = around 0.0125</output>

<gadget id="calculator">1 / (1/80)</gadget>
<output>80</output>

<result>80</result>