Answer:
We bought five 3 3/4 pound bags of bird seed.
A :
Total weight is = 
 pounds of bird seed.
 pounds of bird seed.
In mixed fraction it is : 
 pounds
 pounds
B :
As given, each smaller bag contains 1 1/2 pounds, so 9/4 pounds can make:
=
 = 18/12 = 3/2 bags
= 18/12 = 3/2 bags
C :
We can make 1 full bag and will have left out enough for half of another bag. Half of a 3/2 pound is :
 = 3/4 of a pound.
 = 3/4 of a pound.