Important notes and formula

If the current age of a person is X then N years hence (in future) his age will be (X+N).

Example:

In the year 2016 Salman was 16 years old. What will be his age in the year 2021?

N = 2021 - 2016

= 5 years

So, Salman's age 5 years hence will be (16 + 5) = 21.

If the current age of a person is X then N years ago (in past) his age was (X-N).

Example:

In the year 2010 Salman was 10 years old. What was his age in the year 2005?

N = 2010 - 2005

= 5 years

So, Salman's age 5 years ago was (10 - 5) = 5.

If the current age of a person A is X and person B is N times the age of person A. Then age of person B = NX.

Example:

If the current age of Rocky is 12 years and his older brother Jimmy is 1.5 times older than him. Find the age of Jimmy.

Current age of Rocky X = 12

N = 1.5

Age of Jimmy = NX

= 1.5 x 12

= 18 years.

If the current age of a person A is X and person B is 1/N times the age of person A. Then age of person B = X/N.

Example:

If the current age of Rocky is 12 years and his younger brother Johnny is 1/2 times Rocky. Find the age of Johnny.

Current age of Rocky X = 12

1/N = 1/2

Age of Johnny = X/N = 12/2

= 6 years.

If two ages are in the ratio M : N then we can write them as Mx and Nx.

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