The average of the three numbers A, B, and C is 105, and A:B=2:3, B is C's (4/5), what is the number of B.
甲、乙、丙三个数的平均数为105，且甲：乙=2：3，乙是丙的(4/5)，乙数是多少．
<gadget id="calculator">105 * 3</gadget>
<output>315</output>

<gadget id="calculator">8 + 12 + 15</gadget>
<output>35</output>

<gadget id="calculator">12 / 35</gadget>
<output>12/35 = around 0.342857</output>

<gadget id="calculator">315 * (12/35)</gadget>
<output>108</output>

<result>108</result>