The boys picked 3 1/2 baskets of apples and the girls picked 5 1/2 baskets so how many baskets of apples did the boys and girls pick in all

I will assume we are talking about baskets that are only half full. As opposed to 3 AND 1/2 baskets.

total=amount picked by boys + amount picked by girls
total=3(1/2)+5(1/2)
total=4 baskets <---Answer

if you did mean 3 AND 1/2 baskets then the answer is the following:

total=amount picked by boys+amount picked by girls
= 3+1/2 + 5+1/2
=9 baskets <---Answer

Xis -1/2
y is 35/4.