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(9)
Let, the present age of father is x years and that of his son is y years
By the given conditions,
x + 5 = 3 (y + 5)
⇒ x + 5 = 3y + 15
⇒ x = 3y + 10 .....(i)
x - 5 = 7 (y - 5)
⇒ 3y + 10 - 5 = 7y - 35 [ by (i) ]
⇒ 3y + 5 = 7y - 35
⇒ 7y - 3y = 5 + 35
⇒ 4y = 40
⇒ y = 10
Putting y = 10 in (i) no. equation, we get
x = 3 (10) + 10
⇒ x = 30 + 10
⇒ x = 40
Therefore, the present age of the father is 40 years and that of his son is 10 years.
(10)
Let, the present age of the father js x years and that of his son is y years
By the given conditions,
x - 1 = 8 (y - 1)
⇒ x - 1 = 8y - 8
⇒ x = 8y - 7 .....(i)
x = y²
⇒ 8y - 7 = y²
⇒ y² - 8y + 7 = 0
⇒ y² - y - 7y + 7 = 0
⇒ y (y - 1) - 7 (y - 1) = 0
⇒ (y - 1) (y - 7) = 0
Either y - 1 = 0 or, y - 7 = 0
⇒ y = 1 , y = 7
- Putting y = 1 in (i) no. equation, we get x = 8 (1) - 7 = 8 - 7 = 1
- Putting y = 7 in (i) no. equation, we get x = 8 (7) - 7 = 56 - 7 = 49
Since x = 1 looks inappropriate as the age of the father, we take x = 49
Therefore, the present age of the father is 49 years and that of the son is 7 years.
Heya!!
Let the present age of son be = x
And let the present age of his father be = y
ACCORDING TO THE GIVEN QUESTION!
y+5 = 3(x+5) ... Equation ( i )
FIVE YEARS AGO
y - 5 = 7 ( x - 5 ) ... Equation ( ii )
ADD BOTH THE EQUATIONS WE HAVE!
2y = 10x -20
y = 5x - 10
x = 10years.
y = 40years.
So, the present age of son is = 10years.
And
present age of his father is = 30years.