Critical thinking

My mother still makes tea with the old saying: “one spoon per person and one for the pot”.
We used to buy a packet of tea every week but since grandmother came to live with us we have to buy two packets every fifth week and one otherwise.
How many people were at home before grandmother arrived?
A. 4
B. 5
C. 6
D. 9
E. 11

My confusion is: how can I know how many people can be served tea by 1 tea packet?


You have to assume that they all drink tea once per day
5 weeks =35 days
5 packets = 35(x+1) spoons
6 packets = 35(x+2) spoons

5p=35(x+1) so p=7x+7


So 4 people were at the home before the grandmother arrived