Question

Mary is twice older than her sister.In 5 years time she will be 2 years older than her sister. find how old are they both now?

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Answer 1

$\huge\purple{Required \: Answer :}$

Let,

The Age of Mary Be x years,

The Age of Her Sister Be y years,

From Condition 1,

$x = 2y \\ x - 2y = 0$

From Condition 2,

$( \: x + 5 \: ) = ( \: y + 5 \: ) + 2 \\ x + 5 = y + 7 \\ x - y = 7 - 5 \\ x - y = 2$

Subtract Equation 1 From Equation 2,

$\: \: \: \: \: \: \: x - y = 2 \\ \: \: \: - \: \: \: x - 2y = 0 \\ \: = \: \: \: \: \: \: \: \: \: \: \: \: \: \: y = 2$

Put y = 2 in Equation 2,

$x - y = 2 \\ x - 2 = 2 \\ x = 2 + 2 \\ x = 4$

Hence,

The age of Mary is $\huge{4}$ years,

The age of Her Sister is $\huge{2}$ years.

$\huge{Thanks}$

Answer 2

Step-by-step explanation:

Mary is twice older than her sister. In 5 years time,she will be 2 years older than her sister. find how old are they both now

Solution:

Let present age of Mary's sister=x

Therefore, Present age of Mary=y=2x

After 5 years,

Mary's sister age=x+5

Mary's age=2x+5

According to question,

Mary's age=Mary's sisters age+two years

2x+5=(x+5)+2

2x+5=x+5+2

2x=x+7-5

2x-x=7-5

x=2

Hence, Mary's Sister is 2 years old and Mary is (2x=2*2=4) 4 years old!!

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