The sum of Two-fifths StartRoot 88 EndRoot is 9.78083151. This number is irrational because the square root of 88 is not a perfect square. Therefore, it cannot be expressed as a ratio of two integers and has a non-repeating, non-terminating decimal expansion.
If we simplify the expression to Four-fifths StartRoot 22 EndRoot, then the sum would be 13.38083151. This number is also irrational because the square root of 22 is not a perfect square.
However, if we consider only the coefficient (two-fifths or four-fifths), then the sum would be a rational number. For example, if we add two-fifths and four-fifths, we get a sum of 6/5, which is a rational number.