A sporting goods store sells golf balls in boxes. Each box has 4 compartments of golf balls. Each compartment has 3 golf balls. The store sold 37 boxes on Friday and 42 boxes on Saturday. How many golf balls did the store sell in all? A.
316 golf balls

B.
217 golf balls

C.
789 golf balls

D.
948 golf balls

, 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

isn't it a pentagon? sense [3 (triangle) + 4 (rectangle)] - 2 (triangle and rectangle connected) = 5 (pentagon)