Density equals mas divided by volume. You know the density and mass so use it to solve for the volume.
d= m/v
d= 19.3 g/mL
m= 50g
v=?
Plug it in. 19.3= 50/v
To solve for v you do the opposite of 50 divided by v which is 50 time v.
That cancels v from the right side of the equation. Do the same on the other side(times v)
19.3 * v=50
Now just divide both sides by 19.3 to get v alone.