SOLUTION: Mary is twice as old as Susan and three years older than John. The sum of their ages is 32. How old is Susan?

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Question 260697: Mary is twice as old as Susan and three years older than John. The sum of their
ages is 32. How old is Susan?
Answer by drk(1908) About Me  (Show Source):
You can put this solution on YOUR website!
m = mary
s = susan
J = john
------
(i) m = 2s
(ii) m = j + 3
(iii) m+s+j = 32
step 1 - set (i) = (ii) and solve for j. We get
(iv) 2s = j + 3
(v) j = 2s-3
step - 2 rewrite m and j in terms of s using (i) and (v). We get
(vi) 2s + s + 2s -3 = 32
step 3 - solve for s. WE get
(vii) 5s - 3 = 32
add 3 to get
(viii) 5s = 35
divide by 5 to get
(ix) s = 7
So, susan is 7.