Let the ages of father and son be 6x and x respectively.
From question, (6x + 5) / (x + 5) = 7 / 2

Correct Option: A

Let the ages of father and son be 6x and x respectively.
From question, (6x + 5) / (x + 5) = 7 / 2
⇒ 2(6x + 5) = 7(x + 5)
⇒ (12 - 7) x = 35 - 10
⇒ x = 5
∴ Son's present age = 5 years

Let son's age 1 year ago be x years.
⇒ Father's age 1 year ago = 4x years
∵ 4x + 7 = 2(x + 7) + 9

Correct Option: C

Let son's age 1 year ago be x years.
⇒ Father's age 1 year ago = 4x years
∵ 4x + 7 = 2(x + 7) + 9
⇒ 2x = 23 - 7
⇒ x = 8
Ratio of father's and son's present ages = (4x + 1) : (x + 1) = 33 : 9 = 11 : 3

Let son's age 10 years ago be x years.
∴ father's age 10 years ago = 3x years
∵ 3x + 20 = 2(x + 20)

Correct Option: B

Let son's age 10 years ago be x years.
∴ father's age 10 years ago = 3x years
∵ 3x + 20 = 2(x + 20)
⇒ x = 20
∴ Ratio of their present ages = (3x + 10) : (x + 10) = 70 : 30 = 7 : 3

Let the ages of Laxmi and her mother be 11x and 3x respectively.
From question, 11x - 3x = 24

Correct Option: A

Let the ages of Laxmi and her mother be 11x and 3x respectively.
From question, 11x - 3x = 24
⇒ x = 3

∴ Ratio of their ages after 3 years = ( 3x + 3) : (11x + 3 )
= 12: 36 = 1 : 3

Let A's age be x years, B's age be 2x years and C's age = (x + 17) years

According to the question,
∵ x + 2x + (x + 17) = 185

Correct Option: B

Let A's age be x years, B's age be 2x years and C's age = (x + 17) years

According to the question,
∵ x + 2x + (x + 17) = 185
⇒ 4x = 185 - 17 = 168
∴ x = 42
∴ A's age = 42 years
B's age 84 years
C's age = 42 + 17 = 59 years