Chapter 1 - Introduction to Algebraic Expressions - 1.2 The Commutative, Associative, and Distributive Laws - 1.2 Exercise Set - Page 17: 72

$12+6a+6b$

The distributive law states that $a(b+c)=ab+ac$ (for real numbers $a$, $b$, and $c$). That is, the product of a number and a sum can be written as two products. Therefore, $(2+a+b)6=2(6)+a(6)+b(6)=2\times6+a\times6+b\times6=12+6a+6b$.