SOLUTION: William is 1/6 the age of his father and 5 years older than his sister. If their combined ages are 51 how old is William?

Question 1034660: William is 1/6 the age of his father and 5 years older than his sister. If their combined ages are 51 how old is William?
Found 2 solutions by fractalier, nerdybill:
Answer by fractalier(6550) (Show Source): You can put this solution on YOUR website!
Call the ages of William, father and sister, w, f, and s.
Then we write
w + f + s = 51
but we also know that
w = (1/6)f OR f = 6w
w = s + 5 OR s = w-5
Now substitute and get
w + 6w + w-5 = 51
8w - 5 = 51
8w = 56
w = 7 years old
Answer by nerdybill(7384) (Show Source): You can put this solution on YOUR website!
William is 1/6 the age of his father and 5 years older than his sister. If their combined ages are 51 how old is William?
Let w = William's age
and
f = father's age
s = sister's age
.
w = (1/6)f (eq 1)
w = s+5 (eq 2)
w+f+s = 51 (eq 3)
.
solve eq 1 for f
f = 6w
solve eq 2 for s
s = w-5
plug above into eq 3
w + 6w + w-5 = 51
8w - 5 = 51
8w = 56
w = 7 years old (answer)

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