Question

The difference between the ages of two sisters is 10years.if 15 year ago the elder one was twice as old as the younger one find their presents age

Answer 1

Answer:

Step-by-step explanation: hope it helps!!

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Answer 2

$\huge{\star{Concept\: behind:-}}$

$\textbf{\underline{Linear equation in one variable and logical reasoning.}}$

$\textsf{Let the age of younger sister 15 years ago be {\textbf{X}}}$

$\sf\textsf{So, the age of the elder sister is {\textbf{2x}} as she was twice her younger sister's age.}$

$\sf\textsf{Now, their present ages:-}$

$\sf{Younger\: sister={\boxed{\textbf{\underline{(X+15) years}}}}}$

$\sf{Elder\: sister={\boxed{\textbf{\underline{(2X+15) years}}}}}$

$\huge\textrm{According to the question:-}$

$\sf{The \:difference\: between\: their\: ages\: is\: {\bold{10 \:years.}}}$

$\implies{\textbf{Elder sister's age-Younger sister's age=10 years}}$

$\implies{(2x+15)-(X+15)=10}$

$\implies{2x+15-x-15=10}$

$\implies{2x-x+15-15=10}$

$\implies{\bold{\underline{X=10}}}$

$\sf{The\: present\: ages\: of\: both\: the \:sisters\: are\: {\boxed{\bold{2x+15=2×10+15=35}\: and\: {\boxed{\bold{X+15=10+15=25}}}}}}$

$\sf\textsf{The difference between 35 and 25 is 10, which matches with the information given in the question, hence the answer is correct.}$