After filling your bird feeders, Barbara has 3 1/2 cups of mixed birdseed left. The two bird feeders in the front yard took 4 1/2 cups each. The two feeders in the backyard each took 2 3/4 cups. The two feeders next to the living room window each took 3 1/4 cups. How many mix bird seed did Barbara have before filling the bird feeders?