A: For this equation you would use distributive property leading you to multiply 3x and 2 by 4 giving you a new expression. 12x + 8 - 2. After this you would just simplify the equation by subtracting 2 from 8 giving you 6. This leading to a new equation, 12x + 6.
B: In order to factor the expression you would need to do the reverse of distributive property, finding the GCF, or greatest common factor between the 16 and the 20b. When you do this you result in getting 4 as your GCF. Afterwards you need to divided the numbers by the GCF. Leading you to get 4(5b-4). This is how you would factor the equation.
