Question 167906
Let x = Sam's present age
Let y = Sue's present age
:
Write an equation for each statement:
"Six years ago, Sam was three times as old as Sue."
x - 6 = 3(y-6)
x - 6 = 3y - 18
x = 3y - 18 + 6
x = (3y - 12)
:
" Four years from now Sam will be twice as old as Sue will be."
x + 4 = 2(y+4)
x + 4 = 2y + 8
x = 2y + 8 - 4
x = 2y + 4
:
 Find the present age of each.
:
From the 1st equation, replace x with (3y-12) in the above equation:
3y - 12 = 2y + 4
3y - 2y = 4 + 12
y = 16 yrs is Sue's present age
:
Find x using the the equation: x = 2y + 4
x = 2(16) + 4
x = 36 yrs is Sam's present age
:
:
Check solution in the statement:
"Six years ago, Sam was three times as old as Sue."
36 - 6 = 3(16-6)