The ratio of A's age to B's age is 4:5, what percentage of B's age is A's?
甲的岁数和乙的岁数的比是4：5，甲的岁数是乙的百分之几？
<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<result>4/5 = around 0.8</result>