Question

Mary told her daughter, "seven years ago, I was seven times as old as you were then. Also, three years from now, I shall be three times as old as you will be. "Find the present age of Mary and her daughter. solve by the substitution method.​

Answer 1

Answer:

The present age of Mary is 42 years

The present age of Daughter is 12 years

Step-by-step explanation:

Let the present age of Daughter be x years

Let the present age of Mary be y years

By the first given condition,

7 years ago , daughter age = x-7 years

and Mary's age = y-7 years

y-7 = 7(x-7)

y-7 = 7x -49

7x-y = 42 ---------(i)

By the second given condition,

After three years ,

Daughter's age = x+3

Mary's age= y+3

y+3 = 3(x+3)

y+3= 3x+9

3x-y = -6

y=3x+6 --------(ii)

Substituting value of y in equation (i)

7x- (3x+6)=42

7x - 3x - 6 = 42

4x = 42 + 6

4x = 48

x= 12

Substituting value of x in equation (ii)

y= 3× 12 + 6

y=36+6

y=42

Therefore, present age of Daughter = 12 years

and Mary = 42 years.