Okay so you know how I said you could distribute the -1, let's start from there. So we have (3^-1)/(4^-1).
Now the 3 in the numerator, since it is to the power of the negative one, can now be flipped to the denominator. So we have:
1/(3*(4)^-1).
So we took care of the three, because once you flip it, the negative sign can go away.
Now time to take care of the 4^-1. Since it is in the denominator and 4 is to the power of negative one, we can flip the four to the numerator (but be sure to leave the three, that is no longer to a negative power, alone). So now we have
4/3.
Did that help a little more?