Answer: We can set up a system of equations to represent the information given:
Let x = length of Barbary River
Howler River = x + 230
Gin River = x + 150
Retinal River = x - 30
Total length = x + (x + 230) + (x + 150) + (x - 30) = 19,230
We can then use substitution and the equations above to solve for the length of each river:
x + (x + 230) + (x + 150) + (x - 30) = 19,230
4x + 350 = 19,230
4x = 18,880
x = 4720 (length of Barbary River)
Howler River = x + 230 = 4720 + 230 = 4950 mi
Gin River = x + 150 = 4720 + 150 = 4870 mi
Retinal River = x - 30 = 4720 - 30 = 4690 mi
Explanation: