To solve this, we need to turn this word problem into a system of linear equations. To do this, let's use x to stand for Mr. Fontana's age, and y to stand for his son's age.
The first sentence states that eight years ago, Mr. Fontana was six times as old as his son.
eight years ago = x - 8
Fontana was six times as old as his son = 6(y - 8). Remember, we need subtract 8 from his son's age, which is why I wrote it as 6(y - 8), and his father was 6 times his son's age 8 years ago, which is why I multiplied 6 by y - 8.
Now, putting this all together gives us our first equation:
x - 8 = 6(y - 8)
We can now rewrite this equation in standard form:
x - 8 = 6y - 48 ----->
x - 6y = -48 + 8 ----->
x - 6y = -40 <----- this is our first linear equation
To find our second, we need to turn the second sentence into an equation. It says that in 12 years, Mr. Fontana will be twice as old as his son:
x + 12 = 2(y + 12)
Now, we need to rewrite this equation in standard form:
x + 12 = 2y + 24 ----->
x - 2y = 24 - 12 ----->
x - 2y = 12 <----- this is our second linear equation. We now have our system of equations:
x - 6y = -40
x - 2y = 12
Now we can find the father's age (x) and his son's age (y). First, multiply the second equation by -1, giving us:
x - 6y = -40
-x + 2y = -12
Now we can add both equations together:
x - x - 6y + 2y = -40 + -12 ----->
-4y = -52
Solve for y, by dividing both sides of the equation by -4, giving us:
y = 13
So, now we know the son's age: 13
To find the father's age, replace y in either the first equation or the second equation, with 13. Let's use the first equation:
x - 6(13) = -40 ----->
x - 78 = -40 ----->
x = 78 - 40 ----->
x = 38
Therefore, Mr. Fontana is 38 years old and his son is 13 years old.
