Question

Rahul is 4 times as old as his brother Raj. After 10 years, he will be twice as old as his brother. What is his present age?​

Answer 1

Given :

• Rahul is 4 times as old as his brother Raj.
• After 10 years, he will be twice as old as his brother.

To find :

• Present age of Rahul

Solution :

Let,

• Present age of Raj = x years
• Present age of Rahul = 4x years

Their ages after 10 years,

• Age of Raj = x + 10 years
• Age of Rahul = 4x + 10 years

According to the question,

⠀⠀⠀⇒ 4x + 10 = 2(x + 10)

⠀⠀⠀⇒ 4x + 10 = 2x + 20

⠀⠀⠀⇒ 4x - 2x = 20 - 10

⠀⠀⠀⇒ 2x = 10

⠀⠀⠀⇒ x = 10 ÷ 2

⠀⠀⠀⇒ x = 5

The value of x = 5

Substitute the value of x in the ages of Raj and Rahul.

• Present age of Raj = x = 5 years
• Present age of Rahul = 4x = 4 × 5 = 20 years

Answer 2

Given :

• Rahul is 4 times as old as his brother Raj.
• After 10 years, he will be twice as old as his brother.

To Find :

• Their Present Ages

Solution :

⟼ Let the Present age of Raj be x

⟼ Then Rahul's will be 4x

✰ After 10 years :

⟼ The Present age of Son will be x + 10

⟼ Then Father's age will be 4x + 10

According to the Question :

⟹ Rahul's age = 2 × Raj's age

⟹ 4x + 10 = 2 (x + 10)

⟹ 4x + 10 = 2x + 20

⟹ 4x - 2x = 20 - 10

⟹ 2x = 10

⟹ x = 10/2

⟹ x = 5

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Therefore :

• Rahul's Age = 4x = 4(5) = 20years
• Raj's age = x = 5years

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