Consider $$x$$ as the required rational number
Other number $$ = \dfrac{-3}{5} $$
Here the sum of two numbers is $$2$$
From the question
$$ \dfrac{-3}{5} + x = 2 $$
By further calculation
$$ x = 2 + \dfrac{3}{5} $$
LCM of $$1$$ and $$5$$ is $$5$$
$$ x = \dfrac{2 \times 5 + 3}{5} $$
So we get
$$ = \dfrac{10 + 3}{5} $$
$$ = \dfrac{13}{5} $$
$$ = 2 \dfrac{3}{5} $$