Question

A father is 3 times as old as his son. After 10 year's his age will be double of his son’s age. Find their present ages.

a. 10 years, 30 years

b. 12 years, 36 years

c. 15 years, 45 years

d. 11 years, 33 years ​

Answer 1

See the above attachment for answer.

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Answer 2

Let say:

F= Father’s age

S = Son's age

For (Eq1) Father is three times as old as his son:

F = 3S

For (Eq2) In 10 year time the Father age will be twice as old as his son:

F + 10 = 2(S + 10)

F=2S+20–10

F=2S+10 (Eq2)

Then, lets us substitute the (Eq1) into the (Eq2)

3S=2S+10

3S-2S=10

S=10

Then son is 10 years old.

and Father

F=3S so 3 x 10

Father age is 30 years old.

Answer 3

Let say:

F= Father’s age

S = Son's age

For (Eq1) Father is three times as old as his son:

F = 3S

For (Eq2) In 10 year time the Father age will be twice as old as his son:

F + 10 = 2(S + 10)

F=2S+20–10

F=2S+10 (Eq2)

Then, lets us substitute the (Eq1) into the (Eq2)

3S=2S+10

3S-2S=10

S=10

Then son is 10 years old.

and Father

F=3S so 3 x 10

Father age is 30 years old.