$\begin{array}{lccc} & \text{Amal} & \text{Bimal} & \text{(Amal+Bimal+Kamal)} \\ \text{Time:} & 10\;\text{days} & 8\;\text{days} & 4\;\text{days}\\ \text{Total work:} & \text{LCM(10,8,4)} & = 40\; \text{units} & \\ \text{Efficiency:} & 4 \;\text{unit/day} & 5\;\text{unit/day} & 10\;\text{unit/day} \end{array}$
Efficiency of $\text{Amal + Bimal + Kamal} = 10$
$\Rightarrow 4 + 5 + \text{Kamal} = 10$
$\Rightarrow$ Efficiency of Kamal $ = 10-9 = 1$
Amal, Bimal and Kamal together complete the job in $4$ days and are paid a total amount of $\text{Rs}\; 1000$ as remuneration.
- $10 \longrightarrow \text{Rs}\; 1000$
- $1 \longrightarrow \text{Rs}\; 100$
$\therefore$ The Kamal’s share in rupees is $100.$
Correct Answer $:\text{A}$