(x+2)/(x^2-8x+15)

= x^2-8x+15

= x^2-5x-3x+15

= x(x-5)-3(x-5)

= (x-3)(x-5)

we can write it,

(x+2)/(x-3)(x-5)

= x^2-8x+15

= x^2-5x-3x+15

= x(x-5)-3(x-5)

= (x-3)(x-5)

we can write it,

(x+2)/(x-3)(x-5)