There are 12 pine trees on the side of the road, one of the poplar trees is a pine tree (5/6), and at the same time it is a fir tree (2/3). How many fir trees are there?
路边有松树12棵，杨树的棵树是松树的(5/6)，同时又是杉树的(2/3)．杉树有多少棵？
<gadget id="calculator">5 / 6</gadget>
<output>5/6 = around 0.833333</output>

<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">(5/6) / (2/3)</gadget>
<output>5/4 = around 1.25</output>

<gadget id="calculator">12 * (5/4)</gadget>
<output>15</output>

<result>15</result>