this isn't a riddle.Mandy's age is even
Sandy's age is odd
Together the sum of their ages is 63 how old is each sister?
since Sandy's age is odd, we can write it as: for ...(i used the natural numbers instead of the integers since negative ages make no sense, but whatever).
since Mandy is 25 yrs older than Sandy, Mandy's age is given by:
The sum of their ages is 63, thus we have:
now solve for and you will be able to find their ages