SOLUTION: kim is 1/3 the age of her older sister sue. in 13 years, sue will be one year younger than twice kim's age. how old is sue? Please help me. Thanks!

Question 224466: kim is 1/3 the age of her older sister sue. in 13 years, sue will be one year younger than twice kim's age. how old is sue?
Please help me. Thanks!
Answer by ankor@dixie-net.com(22740) (Show Source): You can put this solution on YOUR website!
Let k = Kim's present age
Let s = Sue's present age
:
Write an equation for each statement:
:
"kim is 1/3 the age of her older sister sue."
k = s
or
s = 3k; may use it this way for substitution
;
" in 13 years, sue will be one year younger than twice kim's age."
s + 13 = 2(k + 13) - 1
Simplify the equation as much as possible
s + 13 = 2k + 26 - 1
s + 13 = 2k + 25
s = 2k + 25 - 13
s = 2k + 12
:
how old is sue?
:
Substitute 3k for s in the above equation, find k
3k = 2k + 12
3k - 2k = 12
k = 12 yrs is Kim's present age
then
s = 3k
s = 3(12)
s = 36 is Sue's present age
;
:
Check our solution in the statement:
"in 13 years, sue will be one year younger than twice kim's age.
36 + 13 = 2(12 + 13) - 1
49 = 2(25) - 1; confirms our solution
:
:
Did this make sense to you?
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