The local fish market is having a sale on whole fish. the prices are as follows:
You can buy an albacore and a barracuda for$21
You can buy a barracuda and a carp for $32
You can buy a carp and a dogfish for $32
You can buy a dogfish and an eel for $37
You can buy an eel and flounder for $31
You can buy a flounder and a gar for $25
You can buy gar and an albacore for $26
Determine the cost of each individual fish
a + b = 21
b + c = 32 or
b = 32 - c so
a + 32 - c = 21
c + d = 32 so
c = 32 - d and
a + 32 - (32 - d) = 21 etc.