a collection of 7 pencils, every week 3 more pencils are added How many weeks will it take to have 3

a collection of 7 pencils, every week 3 more pencils are added How many weeks will it take to have 30 pencils?

Set up a function, P(w), where w is the number of weeks, and P(w) is the total amount of pencils after w weeks. We have:
P(w) = 3w + 7

We want to know what w is when P(w) = 30
3w + 7 = 30

Typing this equation into our search engine, we get:
w = 7.6667

We round up to the nearest integer, so we get w = 8