The point to be noticed here is no two boys can sit together, but girls can, so let us arrange girls first:
                         --G--G--G--G--

These 4 girls can be arranged in 4! ways, upon arranging girls, 5 spaces are created, we can place 4 boys at any 5 places in 5p₄ ways
Therefore answer is 5p₄×4! ways
120×24 = 2,880 ways.