Let the Length of River D be : P
Given : River C is 100 Miles Longer than River D
⇒ Length of River C = P + 100
Given : The Sum of Both Rivers is 5570 Miles
⇒ P + (P + 100) = 5570
⇒ 2P + 100 = 5570
⇒ 2P = 5570 - 100
⇒ 2P = 5470
⇒ P = 2735
⇒ Length of River D is : 2735 Miles
⇒ Length of River C is : (P + 100) = (2735 + 100) = 2835 Miles
