A student walks from home to school and takes the bus back home by the same route. The whole round trip takes 40 minutes. If the speed of the bus is 7 times the speed of the students walking, how many minutes will it take the students to walk back and forth.
一学生从家出发步行去学校，并且按相同的路线乘公共汽车回家．整个来回需要40分钟．如果公共汽车的速度是学生步行速度的7倍，学生来回都步行需要多少分钟．
<gadget id="calculator">7 / 4</gadget>
<output>7/4 = around 1.75</output>

<gadget id="calculator">40 * (7/4)</gadget>
<output>70</output>

<result>70</result>