Well this is kind of difficult because we have no way to determine a constant for each banana; however, we can still formulate an equation to form some sort of solution.
[tex]2 \: lbs \: bananas = 7 \: dollars[/tex]
Divide both sides by two:
[tex]1 \: lbs \: bananas = 3.50 \: dollars[/tex]
Now, we can continue to go forward as long as know how many pounds each banana bunch weighs and how many bananas are in the bunch.
We could say there are "x" bananas in each pound of bananas:
[tex]x \: bananas \div 1 \: lbs \: bananas = 3.50 \: dollars[/tex]
Or:
[tex]b \div 1 \: lbs \: bananas = 3.50c[/tex]
Or to isolate "c":
[tex](b \div 1 \: lbs \: bananas) \div 3.50 = c[/tex]
