Question 979465: a man is four times as old as his son,in four years time,he will be three times as old. what are their ages?
Answer by ikleyn(52817)   (Show Source):
You can put this solution on YOUR website!
Let x be the man's age now, and let y be the son's age now.
Then we have an equation
x = 4y,
according to the condition.
In 4 years the man's age will be x+4, and his son's age will be y+4.
Thus we have the second equation
x + 4 = 3*(y+4),
according to the condition.
So, we need to solve this system of linear equations
 .
To solve it, substitute x from the first equation to the second one. You will have
4y + 4 = 3*(y+4),
4y + 4 = 3y + 12,
y = 12 - 4,
y = 8.
Thus the son age is 8 years now.
Then the man's age is 8*4 = 32 years now.
The problem is solved.
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