Granny's age

Question

1.She is not yet 80, but she is over 50.

2. Last year her age was a multiple of 7, but the year it is a multiple of 6.

HOW OLD IS GRANNY?

Answer 1

Maxine, I hope I can still help!

 

If Granny is over 50 but under 80 and her age is a multiple of 6, then we are looking at 54, 60, 66, 72 and 78.

 

If last year was a multiple of 7, then we have 56, 63, 70, and 77.  Which of those is one less than the multiples of 6?

 

Granny is 78 years old!