Answer :
Mary: x yrs old
Mike: 3x yrs old
In four yrs:
Mary: x+4 yrs old
Mike: 3x+4 yrs old
As the text of task:
3x+4=2(x+4)
3x+4=2x+8
3x-2x=8-4
x=4
Mary is 4 yrs old
Mike: 3x yrs old
In four yrs:
Mary: x+4 yrs old
Mike: 3x+4 yrs old
As the text of task:
3x+4=2(x+4)
3x+4=2x+8
3x-2x=8-4
x=4
Mary is 4 yrs old
x-the age of Mike
y-the age of his sister
x=3y
x+4=2(y+4)
3y+4=2y+8
3y-2y=8-4
y=4 years
x=3*4=12 years
y-the age of his sister
x=3y
x+4=2(y+4)
3y+4=2y+8
3y-2y=8-4
y=4 years
x=3*4=12 years
