The average of the three numbers A, B, and C is 140, where A:B=2:3, B:C=4:5, what is the number of A.
甲、乙、丙三个数的平均数是140，其中甲：乙=2：3，乙：丙=4：5，甲数是多少．
<gadget id="calculator">8 + 12 + 15</gadget>
<output>35</output>

<gadget id="calculator">8 / 35</gadget>
<output>8/35 = around 0.228571</output>

<gadget id="calculator">140 * 3 * (8/35)</gadget>
<output>96</output>

<result>96</result>