Part A:
The area of the rectangle will be the length times the width, so 4•(x+3). Using distributive property, you'll multiply every term inside the parentheses by 4. 
The area of the rectangle can be expressed by 4x+12.
Part B:
Multiply 4•2 and (x+3)•2, then multiply them together. 
8(2x+6) Now use distributive property to find your answer simplified. 
16x+48 is your answer