There are three numbers A, B, and C, and it is known that A:B=3:4, B:C=5:4, and A is 2 less than C, then what is B
有A、B、C三个数字，已知A：B=3：4，B：C=5：4，且A比C少2，那么B是多少
<gadget id="calculator">20 * 2</gadget>
<output>40</output>

<result>40</result>