After a baby elephant is born, its weight increases by an average of 200 kilograms every year. The baby elephant weighed 100 kilograms when it was born, and now it weighs 4100 kilograms. How old is this elephant now?
小象出生后，体重平均每年增加200千克，小象刚出生时重100千克，现在重4100千克．现在这只象几岁了？
<gadget id="calculator">4_100 - 100</gadget>
<output>4_000</output>

<gadget id="calculator">4_000 / 200</gadget>
<output>20</output>

<result>20</result>