Sum of two rational numbers = \(\frac{-1}{2}\)

One number = \(\frac{5}{6}\)

Let the other rational number = x

**Now,**

According to question,

\(\frac{5}{6}\)+ x = \(\frac{-1}{2}\)

\(\Rightarrow\) x = \(\frac{-1}{2}-\frac{5}{6}\)

\(\Rightarrow\) x \(=\frac{-3-5}{6}\)

\(\Rightarrow\) x = \(\frac{-8}{6}\)

In lowest terms,

x \(=\frac{-8÷2}{6÷2}= \frac{-4}{3}\)

**Therefore,** the other rational number is \(\frac{-4}{3}\)