We need to define variables to represent their ages.
Integers are whole numbers, positive, negative and zero.
Consecutive numbers are numbers such as 14,15, 16, 17 ....
Consecutive even numbers are like 12,14,16,18 ....
(They differ by 2)
Let the age of youngest sister be
Middle sister's age is
Oldest sister's age is
Now use the information to form an equation:
Refer back to the definitions
Oldest = x+4 = 12#