SOLUTION: Mary is 12 years old. Her brother Joey is 2 years old. In how many years will Mary be just twice as old as Joey?

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Question 128599This question is from textbook
: Mary is 12 years old. Her brother Joey is 2 years old. In how many years will Mary be just twice as old as Joey? This question is from textbook

Answer by checkley71(8403) About Me  (Show Source):
You can put this solution on YOUR website!
MARY-JOEY
12----2
IN X YEARS MARY=12+X & JOEY=2+X.
(12+X)=2(2+X)
12+X=4+2X
X-2X=4-12
-X=-8
X=8 SO IN 8 YEARS MARY WILL BE TWICE AS OLD AS JOEY.
PROOF
12+8=2(2+8)
20=2*10
20=20
OR MARY WILL BE 20 & JOEY WILL BE 10.