Answer:
The watermelon.
Explanation:
You can convert the unit of either the watermelon or the toddler to pounds of kilograms.
I'll convert them to kilograms.
Watermelon: 19.5 kg
Toddler: 40 pounds [Divide the value by 2.205, this is just a formula]
=40/2.205
=~18.1
Since 19.5 > 18.5, therefore the watermelon is heavier.