SOLUTION: A child is 1/3 the age of an older sibling. The sum of the children's ages is 16. How old is the younger child?

Question 134895: A child is 1/3 the age of an older sibling. The sum of the children's ages is 16. How old is the younger child?
Found 2 solutions by checkley77, dbashant:
Answer by checkley77(12844) (Show Source): You can put this solution on YOUR website!
X/3+X=16
(X+3X)/3=16
4X=3*16
4X=48
X=48/4
X=12 ANSWER FOR THE OLDER CHILD.
12/3=4 AGE OF THE YOUNGER CHILD.
PROOF
4+12=16
16=16

Answer by dbashant(7) (Show Source): You can put this solution on YOUR website!
First write an equation that describes the relationship between the children's ages.
child's age = 1/3 sibling's age
Let's use C for child's age
and S for sibling's age.
So, we have C = 1/3 S
Next, we know the sum of the ages is 16. So, C + S = 16.
Now that we have 2 equations with 2 unknowns, C and S, we can solve.
If we use substituion, we can put 1/3 S from the first equation in place of C in the second equation.
(1/3 S) + S = 16 Then multiply through by 3 to get rid of the fraction.
S + 3S = 48 Then simplify
4S = 48 Then divide by 4 to solve for S.
S = 12
Now that we know S = 12, it is easy to solve for C.
Your answer should give the age of the younger child.
:-)

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