Question

A boy is 5 years older than his sister. How old are they if their ages are in the ratio 4:5

Answer 1

Sorry for the handwriting though

Answer 2

Hello mate.

Thanks for asking this question.

Your answer is =>

as you have given that , sister of that boy is 5 years greater than that boy.

so , at that time , their ratio of ages will be =>

$=> 1 \: :\: 5$

so , we can say that , if the age of boy is "x" years , then age of sister will be "x + 5 " years.

now , at the present time ,

the ratio of them is given as =>

$=> 4 \::\:5 \:=\: 4x\:years \:of \:boy \:and \:5x \:years\:of \:sister.$

now you can see that ,

$=> \boxed{\frac{x}{x+5} = \frac{4}{5}}$

so,

=> x(5) = (x+5)4

=> 5x = 4x + 20

=> 5x - 4x = 20

=> x = 20 years= boys age.

now ,

sister's age = x + 5

so , we say that ,

sister's age = (20) + 5 years. = 25 years.

so ,

$\boxed {boy's\:age\:=20\:years}$

$\boxed {sister's\:age\:=25\:years}$


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