The ratio of the number A to the sum of the numbers A and B is 3:8, the number A is 45, what is the number B?
甲数与甲乙两数和的比是3：8，甲数是45，乙数是多少？
<gadget id="calculator">45 / 3</gadget>
<output>15</output>

<gadget id="calculator">8 - 3</gadget>
<output>5</output>

<gadget id="calculator">15 * 5</gadget>
<output>75</output>

<result>75</result>