$$\frac{16.2}{16.3}<\frac ad<\frac bd<\frac cd<\frac{12.3}{12.4}$$
$$\Rightarrow \frac{32}{48}<\frac ad<\frac bd<\frac cd<\frac{36}{48}$$
$$\Rightarrow \frac{32}{48}<\frac{33}{48}<\frac{34}{48}<\frac{35}{48}<\frac{36}{48}$$
$$a=33,b=34,c=35,d=48\rightarrow a+b+c+d=120$$ olur.