Question

Five year ago, A was thrice as old as B .ten year later ,A will be twice as old as B . The age of A is

Answer 1

Let the present age of A = x year
And present age of B = y year
Five years ago
Age of A = x – 5 years
Age of B = y – 5 years
A was thrice as old as B
X- 5 = 3(y – 5)
X – 5 = 35 – 15
X – 3y = -15 + 5
X – 3 y = - 10 ………..(1)
Ten years later,
Age of A = x + 10
Age of B = y + 10
A will be twice as old as B
X+ 10 = 2(y+10)
X + 10 = 2y + 20
X – 2y = 10 ………..(2)
X – 3 y = - 10 ………..(1)
Subtracting equation (1) from equation (2) we get
Y = 20
Plug this value in equation first we get
X - 3* 20 = -10
X = 60 – 10
X = 50

Hence age of A = 50 years and age of B = 20 years

Answer 2

Answer:

Solution : Present age of B = x years

Present age of A = 5x years

According to question

5x + 10 =3(X+ 10)

5x + 10 = 3x + 30

5x – 3x = 30 – 10

2x = 20

X = 20/2

X = 10

Hence present age of B = 10 years

And present age of A =5x10 = 50 years