An elephant weighs 0.1 tons when it is just born, and its weight is 4.3 tons after 20 years. How many tons does the elephant grow in weight every year on average?
一只象刚出生时的体重是0.1吨，20年后他的体重是4.3吨，这只象平均每年体重增长多少吨？
<gadget id="calculator">4.3 - 0.1</gadget>
<output>4.2</output>

<gadget id="calculator">4.2 / 20</gadget>
<output>0.21</output>

<result>0.21</result>