Question 923817: A father's age is four times that of his son. After 5 years, it will be three times that of his son. How many more years will take if father's age is to be twice that of his son?
Answer by Theo(13342)   (Show Source):
You can put this solution on YOUR website! x = the father's age today,
y = the son's age today.
the father's age is equal to 4 times the son's age today.
x = 4y (first equation)
the father's age will be equal to 3 times the son's age in 5 years.
x+5 = 3*(y+5) (second equation)
since x = 4y, then replace x with 4y in the second equation to get:
4y + 5 = 3 * (y + 5)
simplify to get:
4y + 5 = 3y + 15
solve for y to get y = 10
the son's age is 10 today and will be 15 in 5 years.
the father's age is 40 today and will be 45 in 5 years.
45/15 = 3
the father's age will be 3 times the son's age in 5 years.
what you now know.
x = 40
y = 10
x+5 = 45
y + 5 = 15
in how many more years will the father's age be equal to 2 times the son's age?
z = the number of years until the father's age is equal to 2 times the son's age.
the point where we start is when the father is 45 and the son is 15.
45 + z = 2 * (15 + z)
simplify to get:
45 + z = 30 + 2z
solve for z to get z = 15.
in another 15 years, the age of the father will be 2 times the age of the son.
45 + 15 = 60
15 + 15 = 30
60/30 = 2
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