A train travels from A to B in 4.2 hours (7/9). According to this calculation, how many hours will it take to reach B?
一列火车从甲地到乙地，4.2小时行驶了全程的(7/9)．照这样计算，还要多少小时才能到达乙地？
<gadget id="calculator">7 / 9</gadget>
<output>7/9 = around 0.777778</output>

<gadget id="calculator">4.2 / (7/9)</gadget>
<output>5.4</output>

<gadget id="calculator">5.4 - 4.2</gadget>
<output>1.2</output>

<result>1.2</result>