Step-by-step explanation:
Maybe it should be written as 4 9/10
In a mixed number
Answer:
In year 2039 both the events will happen again.
Step-by-step explanation:
We are given the following in the question:
Family reunion:
Every 7 year
Update the family tree:
Every 6 years
1997 was the year when they had a family reunion as well as they updated their family tree.
We have to find the year in which both the events will occur together.
We find the lowest common multiple of 7 and 6.

Thus, after 42 years both the event will happen again.
Year:

Thus, in year 2039 both the events will happen again.
So,
If you do some simple division, you will find how much each cm costs in each cake.
20cm cake = 67.5 cents/cm
25cm cake = 93.75 cents/cm
Assuming that you cannot order fractions of cakes, the best deal would be to order 5 of the 20cm cakes.
Cost = 13.50 * 5 = $67.50
You will have to pay $67.50 for the cakes if you want the best deal.