Blackhole attracts the light and according to universal law of gravitation: F=GM1M2/R^2
But mass of light is 0 then the after solving the above equation we get F=0
Thrn why is light attracted towards blackhole

Dear Student,
                        Photon has rest mass zero not dynamic . And photon always in motion can observed( i mean experiment can carried with its motion only). In dynamic condition it has mass , momentum and energy  .
                         As 
                             $$\begin{gathered} If frequency of photon is \nu \\ then energy =h\nu \\ and momentum =\frac{h\nu }{c} \\ and mass=\frac{h\nu }{c^2} c is speed of light \end{gathered}$$
That is why it is attracted in black hole .
Regards