Question

5 years before sum of three friend's age was x years, then after y years sum of their ages will be
(A) x + 3y + 15
(B) x - 3y + 15
(C) x + 3y - 15
(D) x - 3y - 15

Answer 1

Answer:

answer is c

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Answer 2

The sum of three friend's age after y years is    x + 3 y + 15

Step-by-step explanation:

Given as :

Statement I

5 years before sum of three friend's age was x years

Let The present age of first friend = a years

Let The present age of second friend = b years

Let The present age of third friend = c years

Let The sum of ages of three friend after y years = m years

According to question

Five years ago

Age of first friend = ( a - 5 ) years

Age of second friend = ( b - 5 ) years

Age of third friend = ( c - 5 ) years

Now,

From statement

The  sum of three friend's age  = x

i.e   ( a - 5 )  + ( b - 5 ) + ( c - 5 )  = x

Or,  a + b + c - 15 = x

Or,  a + b + c = x + 15                    ...............1

Again

Statement II

After y years

Age of first friend = ( a + y ) years

Age of second friend = ( b + y ) years

Age of third friend = ( c + y ) years

Now,

From statement  

The sum of three friend's age after y years = m

i.e   ( a + y )  + ( b + y ) + ( c + y )  = m

Or,  a + b + c  +3 y = m

Or,  a + b + c = m - 3 y               ...............2

From eq 1 and eq 2

      x + 15  =   m - 3 y

i.e    m = x + 15 + 3 y

Or,   m = x + 3 y + 15

So, The sum of three friend's age after y years = m = x + 3 y + 15

Hence, The sum of three friend's age after y years is x + 3 y + 15  Answer