Been trying for so long the way my teacher taught it, but cannot get right answer.

River C : 200 + x
River D: x

200 + x + x = 5,540
combine like terms

200 + 2x = 5,540
subtract 200 from both sides

2x = 5,340
divide both sides by 2 to isolate the variable

x = 2, 670

River C: 200 + x = 200 + 2,670 = 2,870
River D: x = 2,670

2,870 + 2,670 = 5,540

The operation is suck a c@ck? !