The sum of the reciprocals of Rehmans ages, (in years) 3 years ago and 5 years from now is `1/3dot`Find his present age.

Explanation

Let, present age of Rehman =x year
`because` Rehman's age, 3 year ago =(x+3) years
Rehman's age after 5 years =(x+5) years
According to given condition
`(1)/(x-3)+(1)/(x+5)=(1)/(3)`
`implies(x+5+x-3)/((x-3)(x+5))=(1)/(3)`
`implies(2x+2)/(x^(2)+5x-3x-15)=(1)/(3)`
`impliesx^(2)+2x-15=6x+6`
`impliesx^(2)-4x-21=0`
`impliesx^(2)-7x+3x-21=0`
`impliesx(x-7)+3(x-7)=0`
`implies(x-7)(x-3)=0`
`impliesx=7orx=-3`
`impliesx=7" "(because" age cannot be negative")`
So, present age of Rehman =7 years.