It’s simple. The volume of a sphere is V=4/3πr^3.. so you will convert the mm to m okay?? 10mm=1cm .. so do your conversion from here then when you get the radius then you will substitute it into the volume where r is the radius.. so for the first one l changed mm to cm so.. radius is 4cm then l substitute it into the formula so l got 270 after rounding it to the nearest tenth.. pi=22/7 bear in mind. So do the same for the other one