The sum of the three numbers of A, B, and C is 320, A: B: C = 4: 5: 7, what is the value of B
甲乙丙三数之和是320，甲：乙：丙=4：5：7，乙的值是多少
<gadget id="calculator">4 + 5 + 7</gadget>
<output>16</output>

<gadget id="calculator">5 / 16</gadget>
<output>5/16 = around 0.3125</output>

<gadget id="calculator">320 * (5/16)</gadget>
<output>100</output>

<result>100</result>