36.01-(7.63+▲)=21.6, use the tree diagram to calculate, what is the number represented by ▲.
36.01-(7.63+▲)=21.6，利用树状算图推算，▲表示的数是多少．
<gadget id="calculator">36.01 - 21.6 - 7.63</gadget>
<output>6.78</output>

<result>6.78</result>