Answer:
"y + (y + 4)"
Explanation:
If we need to find the sum of Mala's and sister's ages, then we know that "y" will have to be part of the answer. her sister is 4 years older, so we will need to represent her age as "y + 4". We also need to make sure we have "y + 4" in parenthesis, because we need to do that Expression first. So, if we add all of this into our equation, we end up with the equation "y + (y + 4)".