There are 4 machines with the same work rate. If it took kk

The workrate of a mixture has inverse proportion
$$i.eAmount\ of\ workdone\ (W)=\frac{1}{time\ taken\ \left(T\right)}$$
$$or\ \frac{W1}{W2}=\frac{T2}{T1}$$
Let the amount of workdone by a machine be x.
Therefore, three machines do 3x work in the same time and four machines do 4x work.
$$=>\frac{3x}{4x}=\frac{k-2}{k}$$
$$or\ \frac{3}{4}=\frac{k-2}{k}$$
$$Cross\ multiply$$
$$we\ have,\ 4k-8=3k$$
$$k=8$$
Hence the correct option is e