To solve for #color(orange)v# you need to first isolate it on one side of the equation. This equation is set up to leave the #color(orange)v# on the right side.
In the equation, #color(orange)v# is being divided by #color(brown)16#. To solve the equation, we need to do the opposite -- which is multiplying by #color(brown)16#.
#color(red)4=color(orange)v/color(brown)16#
#color(red)4*color(brown)16=(color(orange)v/color(brown)16)*color(brown)16#
#color(red)64=color(orange)v#