Bottles of sparkling water usually cost 1.69 each each. This week they are on sale for 4 for $5. You bought one last week and one this week. Did you pay more or less for the battle this week? How much more or less?

1.69×4 is 6.76, but 4 bottle for 5 dollars is better. you paid less for the deal. less money by 1.76

, and

for

step-by-step explanation:

we can analyze the pattern at which the terms increase. let us denote , , , so that we can call

note the following:

the pattern: to get the next term value, we just add the next term number (e.g. 1st, 2nd, to the previous term value (term values are the given numbers in the question, 1, 3, 6, 10, 15,

from , to get to , we add

from , to get to , we add

etc.

we need to form a recursive formula, a formula that has the next term as a function of the previous term. so a possible recursive formula can be

, and for