The ratio of the numbers A and B is 2:7, and their average is 45, what is the number B?
甲乙两数的比是2：7，且它们的平均数是45，那么乙数是多少
<gadget id="calculator">7 + 2</gadget>
<output>9</output>

<gadget id="calculator">2 / 9</gadget>
<output>2/9 = around 0.222222</output>

<gadget id="calculator">45 * (2/9) * 7</gadget>
<output>70</output>

<result>70</result>