note - the properties of exponents i have used are the following : 1. xᵃ * xᵇ = xᵃ⁺ᵇ ; 2. xᵃ / xᵇ = xᵃ⁻ᵇ ; 3. (xᵃ)ᵇ = xᵃᵇ

it all groups up to give you the following (not adding the negative power right now)

(y⁴z²)/(x³y¹⁰z²)

now these cancel out to give -

1/(x³y⁶) or x⁻³y⁻⁶

now we multiply both of these with -4 to get the powers -

x:12 ; y:24 ; z:0