3 bags and an 18 dollar bird feeder
cost=cost of bird seed+cost of bird feeder
cost=cost of bird seed+18
cost=45
45=cost of bird seed+18
subtract 18 from both sides
27=cost of bird seed
the bird seed came in 3 bags and each bag cost the same so
27=3 times cost of 1 bag of bird seed
divide by 3
9=cost of 1 bag of bird seed
answer is $9.00