Wave Optics

In Young's double slit experiment, the wavelengths of red and blue lights used are $7.5 \times 10^{-5} \mathrm{~cm}$ and $5 \times 10^{-5} \mathrm{~cm}$ respectively. If $n$th bright fringe of red color coincides with $(n+1)$ th bright fringe of blue colour, then the value of ' $n$ ' is