SOLUTION: Please help me solve this word problem. Anna is 12 years old, and her mother is three times as old as anna. How many years ago was her mother four times as old as anna? Thank you v

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Question 797162: Please help me solve this word problem. Anna is 12 years old, and her mother is three times as old as anna. How many years ago was her mother four times as old as anna? Thank you very much!
Answer by mohanraj04(12) About Me  (Show Source):
You can put this solution on YOUR website!
given that
anna is 12 years old
A=12---------equ:1
where A is age of anna
her mother is three times as old as anna
M=3A---------Equ:2
by substituting equ:1 in equ:2 we get
M=3*12
M=36
therefore the present age of mother is 36 years
let X be the no. of years before her mother four times as old as anna
therefore 4[A-X]=M-X----------EQU:3
by substituting A=12 and M=36 in equ:3 we get
4[A-X]=M-X
4[12-X]=36-X
48-4X=36-X
-4X+X=36-48
-3X=-12
3X=12
X=12/3
X=4
therefore 4 years ago mother four times as old as anna