Question

after 12 years I shall be 3 times old as I was 4 year ago . find their present ages.

Answer 1

let her age = x
after 12 years age = 12 + x
four years ago age = x - 4
linear equation from give data will be
12 + x = 3(x-4)
12+x = 3x-12
12+12 = 3x - x
24 = 2x
x = 24/2
x= 12

it can be verified.
for years ago age = 8
after 12 years age = 24
24 is 3 times 8



hope it helps xD

Answer 2

Letting x = present age

 

x + 12  will be my age 12 years from now.

3(x-4)  will be three times as old as I was 4 years ago

 

x+12 = 3(x-4)

Solve for x

 

x+12 = 3x - 12

subtract x from both sides

12 = 2x - 12

add 12 to both sides

24 = 2x

divide both sides by 2

12 = x

 

My present age is 12 years

 

Check:  x+12 = 3(x-4)

          12+12 = 3(12-4)

             24 = 3(8)

             24 = 24

This balances and answer is correct