Answer:
Let the other rational number be represented by x.
According to the problem, we know that the sum of the two rational numbers is 8/5. Therefore, we can write:

To solve for x, we can isolate it on one side of the equation by subtracting -2/5 from both sides:

Simplifying the right-hand side by finding a common denominator, we get:

And simplifying the fraction, we get:

Therefore, the other rational number is 2.