Li Hui weighed 3.25 kg when he was born, and 7 kg after 3 months. How many kilograms does Li Hui's weight increase on average every month?
李辉出生时体重3.25千克，3个月后体重是7千克．李辉的体重平均每月增长多少千克？
<gadget id="calculator">7 - 3.25</gadget>
<output>3.75</output>

<gadget id="calculator">3.75 / 3</gadget>
<output>1.25</output>

<result>1.25</result>