The sum of the two numbers of A and B is 8.5. If the decimal point of A is moved to the right, it is exactly equal to 7 times of B. What is the number B.
甲乙两数的和为8.5，如果甲数的小数点向右移动一位，就正好等于乙数的7倍．乙数是多少．
<gadget id="calculator">10 / 7</gadget>
<output>10/7 = around 1.428571</output>

<gadget id="calculator">1 + (10/7)</gadget>
<output>17/7 = around 2.428571</output>

<gadget id="calculator">8.5 / (17/7)</gadget>
<output>3.5</output>

<gadget id="calculator">3.5 * (10/7)</gadget>
<output>5</output>

<result>5</result>