Question 287627
32 for mother 
56 for grandfather

You are correct.  ok
Let x be the age of the Nathan. Mother's age is 4x
7x is age of Grandfather

Soo Mother's age is 4(8) = 32
Grandfather's age is 7(8) =56

Now your instructor may be looking for this 4x is mother's age in comparison to Nathan's age so 
Nathan's age is 1/4 Mother's age. Nathan's age is 1/7 Grandfather's age. Does this help further?