18 3 423 +223 =

$$4\frac{18}{23} + 2\frac{3}{23} = (4+2) + (\frac{18}{23} + \frac{3}{23}) = 6 + \frac{21}{23} = 6\frac{21}{23}$$

Ответ: $$6\frac{21}{23}$$