Answer:
River D - 2580 miles
River C - 2980 miles
Step-by-step explanation:
Let the length of River D be represented with x
length of river C = 400 + x
total length of both rivers = 5560
x + 400 + x = 5560
2x + 400 = 5560
collect like terms
2x = 5560 - 400
2x = 5160
divide both sides of the equation by 2
x = 5160 / 2
x = 2580
length of river c = 400 + 2580 = 2980
