Derek pays $120 a month towards his new cell phone. After 7 months, Derek has paid 85% of the total cost of his phone. What is the total cost, in dollars of the new cell phone?

answer: i'm great at algebra

~coco

step-by-step explanation:

, 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

could you provide figure.

hi do you need an answer for your question?

step-by-step explanation: