Can someone please help me with this 7g^-2/g^4

When you have a negative exponent, you move the variable with the negative exponent to the other side of the fraction to make the exponent positive.

For example:

 or  x³

or

When you multiply a variable with an exponent by a variable with an exponent, you add the exponents together. (The variables have to be the same in order to combine them)

For example:

   (The variables(x and y) are different, so you can't combine them)

 or y²

  First make all the exponents positive

   (This is as far as you can simplify)