The library sells 376 books at its annual used-book sale. the sale takes in a total of $2119. children's books cost $4 each, and adult books cost $7 each. let x = number of children's books sold, and let y = the number of adult books sold. write a system of equations to model this situation.

, 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

believe it or not anna is correct good job anna give me a fist bump there u go gal