The ratio of the numbers A and B is 7:2, the number B is 70, what is the number A?
甲乙两数的比是7：2，乙数是70，甲数是多少．
<gadget id="calculator">70 / 2</gadget>
<output>35</output>

<gadget id="calculator">35 * 7</gadget>
<output>245</output>

<result>245</result>