Use a rope to measure the height. Fold the rope into 4 equal sections. When the lower end touches the ground, the upper end is 1 meter higher than the wall. Fold the rope into 5 equal sections. When the lower end touches the ground, the upper end is 1/3 higher than the wall. In this case, how high is the wall?
用一根绳子量高．把绳子折成相等的4段，当下端碰到地时，上端高出墙1米，把绳子折成相等的5段，当下端碰到地时，上端高出墙(1/3)，根据这种情况，墙高多少米？
<gadget id="calculator">20 / 3</gadget>
<output>20/3 = around 6.666667</output>

<gadget id="calculator">(20/3) - 4</gadget>
<output>8/3 = around 2.666667</output>

<gadget id="calculator">4 / (8/3)</gadget>
<output>3/2 = around 1.5</output>

<result>3/2 = around 1.5</result>