SOLUTION: Kathy is 12 years younger than Jed. If the sum of their ages is 42, how old is Kathy?

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Question 710709: Kathy is 12 years younger than Jed. If the sum of their ages is 42, how old is Kathy?
Answer by MathLover1(20849) About Me  (Show Source):
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let Kathy's age be x and Jed's age y
if Kathy is 12 years younger than Jed, then we have
x=y-12.....eq. 1

if the sum of their ages is 42, then we have

x%2By=42.....eq. 2.......substitute x from eq. 1

y-12%2By=42.......solve for y

2y-12=42

2y=42%2B12

2y=54

y=54%2F2

highlight%28y=27%29

go back to x=y-12.....eq. 1, substitute y and solve for x

x=27-12

highlight%28x=15%29....so, Kathy is 15 years old