Since the average weight of a coconut is 2.22 kg less than a watermelon, its average weight is
[tex]4.61-2.22=2.39[/tex]Let n be the number of coconuts and watermelons. The total weight of n coconuts and n watermelons is
[tex]4.61n+2.39n = 7n[/tex]
If we want this total to be 140, we have
[tex]7n=140 \iff n=\dfrac{140}{7}=20[/tex]
So, you have 20 coconuts and 20 watermelons.