Friday puzzler, the solution.

By Morwenna Evans Monday, April 14, 2014

Friday Puzzler: The solution...

On Friday, we asked you the rather tricky problem:

My grandson is about as many days as my son in weeks.

My grandson is as many months as I am in years.

My grandson, my son and I together are 120 years.

Today, we're going to reveal the solution and show you how to get there.

So...

Let g = grandson’s age s = son’s age m = my age

We will first break down each part of the question and write it algebraically in terms of g, s and m.

‘My grandson is about as many days as my son in weeks’ s=7g

‘and my grandson is as many months as I am in years’ 12g=m

‘my grandson, my son and I together are 120 years’ g+s+m=120

Using g+s+m = 120 we can substitute in what we found for s and m g+7g+12g=120

20g=120

g=6

s=7g=7(6)=42 years

m=12(6)=72 years

So the answer is 72!