The average of the two numbers A and B is 25, the ratio of A to B is 3:4, how much less is A than B.
甲乙两个数的平均数是25，甲数与乙数的比是3：4，甲数比乙数少多少．
<gadget id="calculator">3 + 4</gadget>
<output>7</output>

<gadget id="calculator">2 / 7</gadget>
<output>2/7 = around 0.285714</output>

<gadget id="calculator">25 * (2/7)</gadget>
<output>50/7 = around 7.142857</output>

<result>50/7 = around 7.142857</result>