Specifying △ as a mathematical operation symbol makes the following formulas valid: 2△3=7, 2△4=10, 2△5=13, 3△5=12, 4△5=11, 5△5=10 , then (2△1)△8=how many.
规定△作为一种数学运算符号，使下列各式成立：2△3=7，2△4=10，2△5=13，3△5=12，4△5=11，5△5=10，则(2△1)△8=多少．
<gadget id="calculator">3 * 8</gadget>
<output>24</output>

<gadget id="calculator">1 * 3</gadget>
<output>3</output>

<gadget id="calculator">3 - 2</gadget>
<output>1</output>

<gadget id="calculator">24 - 1</gadget>
<output>23</output>

<result>23</result>