Marlene S. answered 12/30/15
Tutor
New to Wyzant
Let's first define some variables
S = grandson
F = father
G = grandfather
We know from the first sentence that
S + F + G = 110
From the 2nd sentence
G = 12S
Finally from the 3rd sentence
52F = 365S
Since the only variable to appear in all 3 equations is S, lets isolate the variable F in the 3rd equation. Notice that the variable G is already isolated in equation 2.
52F = 365S
Dividing both sides by 52
F = 7.019S
Now let's use the equations for F and G and substitute them into the first equation. This way the only variable in the 1st equation will be S
S + 7.019S + 12S = 110
Combining terms
20.019S = 110
Divide both sides by 20.019
5.5
So the grandson is 5.5 years old, which is 66 months
Using equation 2,
G = 12S
G = 12 (5.5) = 66
So the grandfather is 66 years old
Finally how old is the father?
Using the first equation again
S + F + G = 110
5.5 + F + 66 = 110
F = 110 - 66 - 5.5 = 38.5
The father is 38.5 years old.