look at the numbers first
8/2 = 4
so there's a 4 on top of the fraction bar
now look at the v's
v^4 / v^-2
a negative exponent sort of means 'put it on the other side of the fraction bar and make the exponent positive'
v^4 * v^2 / 1
dividing by 1 just goes away, leaving this
v^4 * v^2
v^6
now just put the number and the v's together like this
4v^6
that's the answer.