1. Given (12+3)x, we can sum the numbers in the parenthesis to get 15x
2. Given 12x+3x, we can factor x to get (12+3)x and get the same as 1.
3. Given (12+3x)x, we have to distribute the x and we have 
4. This expression is already simplified.
Its the third one im pretty sure
Answer:
a
Step-by-step explanation:
multiply both members in the pharanthesis by 6: 6*3+6*g= 18+6g