19 × 12 + 19 = 19 × (12 + _____)
By distributive property, we know that if a, b and c are whole numbers,
Then, a × (b + c)= (a × b) + (a × c)
19 × 12 + 19 = 19 × 12 + 19 × 1
19 × 12 + 19 = 19 × (12 + 1)