I just answered a similar question from you on this topic, that explanation is slightly more complete.
v^4/v^12
Dividing by an exponential term is the same as multiplying by that term after changing the sign of its exponent
v^4 v^-12
multiplying two terms with a common base is accomplished by adding their exponents.
v^(4 + -12)
= v^(4-12)
= v^(-8)
but you are required to write your answers with positive exponents only so convent the multiplication (1)(v^-8) to a division by again changing the sign of the exponent.
(1) (v^-8) = 1/v^8
Again, merely answering the problem is far easier than explaining it.
Four ys on top and twelve ys on the bottom. Four on the top factor out four on the bottom, leaving none on top (just a one which is always a factor of the numerator) and eight on the bottom.
