The ratio of A, B, and C is 3:4:5, and the number of A is 10 less than the number of C. What is the B number?
甲、乙、丙三数的比为3：4：5，甲数比丙数少10．乙数是多少？
<gadget id="calculator">5 - 3</gadget>
<output>2</output>

<gadget id="calculator">10 / 2</gadget>
<output>5</output>

<gadget id="calculator">4 * 5</gadget>
<output>20</output>

<result>20</result>