Answer:
River C. is 3,085 miles long.
River D. is 2,485 miles long.
Explanation:
1. Divide 5,570 by 2. Your answer will be 2,785.
2. Add 300 to 1 of your 2,785, and subtract 300 from the other.
3. You will have 3,085 and 2,485. If you add them together, you will have 5,570. This confirms that these two numbers are your answers.
4. You have your answer!