××\(F=m \times a\)×
50N is your force and the acceleration is -9.8m/s^2 due to gravity.
So, you just plug that in.
\(50 N=m\times-9.8m/s^2\\
\frac{50}{-9.8}=m\\
m=-5.102\)
BUT you know that mass cannot be negative, so you just disregard the negative sign and the mass of the rock is 5.102 grams.
