The average of the three numbers A, B, and C is (3/4), and the average of the two numbers B and C is (5/6). What is the number of A?
甲、乙、丙三个数的平均数是(3/4)，乙、丙两数的平均数是(5/6)，甲数是多少．
<gadget id="calculator">3 / 4</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">(3/4) * 3</gadget>
<output>9/4 = around 2.25</output>

<gadget id="calculator">5 / 6</gadget>
<output>5/6 = around 0.833333</output>

<gadget id="calculator">(5/6) * 2</gadget>
<output>5/3 = around 1.666667</output>

<gadget id="calculator">(9/4) - (5/3)</gadget>
<output>7/12 = around 0.583333</output>

<result>7/12 = around 0.583333</result>