Answer
АлександрThe correct choice:
My sister is 15 months old.
We have to look at the assignment as an equation.
Suppose your sister's age is "X."
Now we can create an equation:
X+5 = 5*X.
Let's solve this equation.
5*X - X = 5
4*X = 5
X = 5/4
Х = 15/12
Since there are 12 months in a year, we can say that the sister is 15 months.
Answer: 15 months.