Question

Five yrs ago father age was 4 times his son age now the sum of their age is 45 find their present age

Answer 1

$\huge \mathbb{ANSWER}$

Step-by-step explanation:

$\sf{Let \: the \: age \: of \: \: father \: be \: x \: years}$

$\sf{age \: of \: his \: son \: be ( 45 - x ) years}$

$\rm \red{Five \: years \: ago}$

$\tt{Age \: of \: father = ( x - 5 ) years}$

$\tt{Age \: of \: his \: son =}$

$\tt{( 45 - x - 5 ) years = ( 40 - x ) years}$

Product of their ages five years ago = 4 × father's age five years ago

$\rm{(x - 5)(40 - x) =4(x - 5)}$

$\rm{(x - 5)(40 - x) = 4(x - 5)}$

$\rm{40 - x = 4}$

$\rm{40 - 4 = x}$

$\rm{36 = x}$

Present age of father = x years = 36 years

Present age of his son = ( 45 - x ) = ( 45 - 36 ) = 9 years

$\rm \underline \red{36 \: and \: 9 \: years}$

Answer 2

Answer:

let the age of son = x

let the father age = 4 + x

sum of their ages = x ( 4+× )

= 4x + x square

according to the problem sum of their ages = 45

4x + x square = 45

x square + 4x - 45 =0

x square -5x + 9x - 45 = 0

x ( x - 5) + 9(x - 5) = 0

(x + 9) or ( x- 5) =0

x+9=0

x = -9

x-5=0

x=5

x can't be negative

so x is 5

present age of sun is x is