Two perfectly stirred tanks with capacities of $1\mathrm{.}5$ and $0\mathrm{.}75$ m$3$ are connected in such a way that the effluent from the first passes into the second. Both tanks are initially filled with salt solution $0\mathrm{.}5$ kg$/$L in concentration. If pure water is fed into the first tank at a rate of $75$ L$/$min$,$ determine the salt concentration in the second tank after $10$ minutes?