y^2 -10y+9 = (y-9)(y-1) (by factorization)

5y^2-32y-21 = 5y^2-35y+3y-21 = 5y(y-7)+3(y-7) = (5y+3) (y-7)

so on multiplying the two fractions the denominators will be gone and the numerator left will be:

(5y+3)(y-1) = 5y^2 -5y+3y-3 = 5y^2-2y-3

Hope you got ur answer,

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