Question 970301
Make 2 equations given the information.


Kim's sister is five years older than three times Kim's age


Kim's sister's age = y
Kim's age = x


{{{y=3x+5}}}
five years older than three times kim's age is equivalent to 5 plus 3 times x


The sum of their ages is 13
{{{x+y=13}}}


plug in the first equation to the second.
{{{y=3x+5}}}
{{{x+y=13}}}
{{{x+(3x+5)=13}}}
{{{4x+5=13}}}
{{{4x=8}}}
{{{x=2}}}
Kims age is currently 2. In 7 years her age will be 9.


The answer is 9.



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