how can i solve that equation by factoring

Answer:
[tex]y = {x}^{2} + 8x + 15 \\ factors \: = 3 \: and \: 5 \\ y = {x}^{2} + 3x + 5x + 15 \\ y = x(x + 3) + 5(x + 3) \\ y = (x + 5)(x + 3) \\ either \: (x + 5) = 0 \: or \: (x + 3) = 0 \\ x = - 5 \: and \: - 3[/tex]