y2-19y+60= a2-8a-20=

(y-15)(y-4)
(a-10)(a+2)

y² - 4y - 15y + 60
= y (y - 4) - 15(y - 4)
= (y-15)(y-4)

a² - 10a + 2a - 20
= a(a - 10) + 2(a - 10)
= (a + 2)(a - 10)