The expression would be 
after the negative exponents have been removed.
A negative exponent basically tells us to "flip" the side of the fraction it's on. This means that y⁻⁶ on the numerator would go to the denominator, and that x⁻⁴ on the denominator would go to the numerator. This gives us:
A negative exponent basically tells us to "flip" the side of the fraction it's on. This means that y⁻⁶ on the numerator would go to the denominator, and that x⁻⁴ on the denominator would go to the numerator. This gives us: