Factor the quadratic $x^2 - 13x + 30$.

Find two numbers that multiply to $30$ and add to $-13$:

$(-10)(-3) = 30 \quad \text{and} \quad (-10) + (-3) = -13 \; \checkmark$

Therefore:

$x^2 - 13x + 30 = (x - 10)(x - 3)$