Question 253433
j = john's age
m = mary's age


j+m = 59


if john is older than mary, then:


j-m = 33


from this second equation we can solve for j in terms of m to get:

j = m + 33


we can substitute this in the first equation to get:


j + m = 59 becomes (m+33) + m = 59 which becomes 2m+33 = 59.


subtract 33 from both sides of this equation to get:


2m = 59-33 = 26


divide both sides of this equation by 2 to get m = 13


since j = m + 33, this means that j = 46


46 + 13 = 59


john is 46
mary is 13


we could only do this because we knew that john was older than mary.


if mary was older than john, then the results would be reversed.


just knowing the difference in the ages wasn't enough.


we had to know who was older.