SOLUTION: Six years ago bob was four times as old as Mary. In four years he will be twice as old as Mary. How old are they? Six years ago Bob = 4Mary

SOLUTION: Six years ago bob was four times as old as Mary. In four years he will be twice as old as Mary. How old are they? Six years ago Bob = 4Mary - 6 In four years Bob = 2Mary +

Question 151380: Six years ago bob was four times as old as Mary. In four years he will be twice as old as Mary. How old are they?
Six years ago
Bob = 4Mary - 6
In four years
Bob = 2Mary + 4
4M - 6 = 2M + 4
2M = 10
Mary = 5 years old
Substitute both equations with 5, and Bob is 14
I just want to know if that is right or wrong?
Found 2 solutions by oscargut, stanbon:
Answer by oscargut(2103) (Show Source): You can put this solution on YOUR website!
Six years ago bob was four times as old as Mary. In four years he will be twice as old as Mary. How old are they?
B= Bob's age now
M= Mary's age now
You did it wrong you have to start like this:
B-6=4(M-6)
B+4=2(M+4)
solving we have
B=26 and M=11
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
Six years ago bob was four times as old as Mary.
In four years he will be twice as old as Mary.
How old are they?
-----------
Let Mary's age now be "m".
Let Bob's age now be "b".
---------------------------
6 yrs. ago equation:
(b-6) = 4(m-6)
------------------------------
4 yrs. from now equation:
b = 2m
--------------------------
Substitute to solve for "m".
(2m-6) = 4(m-6)
2m-6 = 4m-24
2m = 18
m = 9 yrs old (Mary's age now)
-------------------
Since b = 2m, b = 2*9 = 18 yrs old (Bob's age now)
===========================
Cheers,
Stan H.

RELATED QUESTIONS
six years ago bob was four times as old as mary. in four years he will be twice as old as (answered by bnyken)
6 years ago bob was 4 times as old as Mary. In 4 years he will be twice as old as Mary.... (answered by 90887896,richard1234)
Six years ago John was four times as old as his sister Mary in four years time you will... (answered by ikleyn,greenestamps)
Mary is twice as old as Rachel will be in seven years. Four years ago, Mary was four... (answered by ankor@dixie-net.com)
six years ago, jim was four times as old as fe. in four years, he would be twice as old... (answered by Maths68,dragonwalker)
six years ago Jun was 4 times as old as Joan. In four years, he would be twice as old as (answered by sudhanshu_kmr)
Mike is three times as old as his little sister mary. in four years, he will be twice as... (answered by jorel1380)
six years ago, rosa was four times old as her daughter. Ten years from now, she will be... (answered by mananth)
Lucy is four times as old as Mary. In twenty years Lucy will be three times as old as... (answered by sofiyac)