Question

The river C is 400 miles longer than River D. If the sum of their heights is 5,580 miles, what is the length of each river

Answer 1

the length of each river is 2,790 and how i got that is by taking 5,580 and dividing by the rivers to get the length of each one... let me know if this helped thanks....

Answer 2

c=d+400
c+d=5,580

2d+400=5,580
2d=5,180
d=2,590

c=2,590+400
c=2,990

Check:
2,990+2,590=5,580

River c is 2,990 miles long, and River D is 2,590 miles long