Three boxes weigh $9\dfrac{1}{2}$ kg, $14\dfrac{1}{5}$ kg and $18\dfrac{3}{4}$ kg respectively. A porter carries all the three boxes. What is the total weight carried by the porter?

Given, weight of three boxes = $9\dfrac{1}{2}$ kg, $14\dfrac{1}{5}$ kg and $18\dfrac{3}{4}$ kg

LCM of 2, 5 and 4 = 20

Total weight

$\Rightarrow 9\dfrac{1}{2} + 14\dfrac{1}{5} + 18\dfrac{3}{4}\\[1em] \Rightarrow \dfrac{19}{2} + \dfrac{71}{5} + \dfrac{75}{4}\\[1em] \Rightarrow \dfrac{19 \times 10}{2 \times 10} + \dfrac{71 \times 4}{5 \times 4} + \dfrac{75 \times 5}{4 \times 5}\\[1em] \Rightarrow \dfrac{190}{20} + \dfrac{284}{20} + \dfrac{375}{20}\\[1em] \Rightarrow \dfrac{190 + 284 + 375}{20}\\[1em] \Rightarrow \dfrac{849}{20}\\[1em] \Rightarrow 42\dfrac{9}{20}$

Hence, the total weight carried by the porter = $42\dfrac{9}{20}$ kg.