SOLUTION: Kierra is three times as old as the building she lives in. In twenty years, she will be tow times the age of her building. How old is Kierra now?

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Question 703941: Kierra is three times as old as the building she lives in. In twenty years, she will be tow times the age of her building. How old is Kierra now?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +k+ = Kierra's age now
Let +b+ = the building's age now
given:
(1) +k+=+3b+
(2) +k+%2B+20+=+2%2A%28+b+%2B+20+%29+
--------------------------
Substitute (1) into (2)
(2) +3b+%2B+20+=+2%2A%28+b+%2B+20+%29+
(2) +3b+%2B+20+=+2b+%2B+40+
(2) +b+=+40+-+20+
(2) +b+=+20+
And, since
(1) +k+=+3b+
(1) +k+=+3%2A20+
(1) +k+=+60+
Kierra is 60
check answer:
(2) +k+%2B+20+=+2%2A%28+b+%2B+20+%29+
(2) +60+%2B+20+=+2%2A%28+20+%2B+20+%29+
(2) +80+=+2%2A40+
(2) +80+=+80+
OK