Question

In 2007, there were 31 laptops

Answer 1

Answer:

$l=31+20(y-2007)$

where $l$ is the number of laptops, and $y$ is the year.

in 2017: $l=231$

Step-by-step explanation:

I will define the variable $x$ as the number of years that passed since 2007.

Since the school buys 20 lapts each year, after a number $x$ of years, the school will have

$20*x$ more laptops.

and thus, since the school starts with 31 laptops, the equation to model this situation is

$l=31+20*x$

where $l$ is the number of laptops.

since x is the number of years that have passed since 2007, it can be represented like this:

$x=y-2007$

where $y$ can be any year, so the equation to model the situation using the year:

$l=31+20(y-2007)$

and this way we can find the number of laptos at the end of 2017:

$y=2017$

and

$l=31+20(y-2007)$

$l=31+20(2017-2007)\\l=31+20(10)\\l=31+200\\l=231$