It is known that the ratio of number A to number B is 5:6, and the ratio of number B to number C is 8:7. When the number B is 12, what is the sum of numbers A and C?
已知甲数与乙数的比是5：6，乙数与丙数的比是8：7，当乙数是12时，甲数和丙数的和是多少？
<gadget id="calculator">5 / 6</gadget>
<output>5/6 = around 0.833333</output>

<gadget id="calculator">12 * (5/6)</gadget>
<output>10</output>

<gadget id="calculator">7 / 8</gadget>
<output>7/8 = around 0.875</output>

<gadget id="calculator">12 * (7/8)</gadget>
<output>21/2 = around 10.5</output>

<gadget id="calculator">10 + (21/2)</gadget>
<output>41/2 = around 20.5</output>

<result>41/2 = around 20.5</result>