Answer:
[tex]l=31+20(y-2007)[/tex]
where [tex]l[/tex] is the number of laptops, and [tex]y[/tex] is the year.
in 2017: [tex]l=231[/tex]
Step-by-step explanation:
I will define the variable [tex]x[/tex] as the number of years that passed since 2007.
Since the school buys 20 lapts each year, after a number [tex]x[/tex] of years, the school will have
[tex]20*x[/tex] more laptops.
and thus, since the school starts with 31 laptops, the equation to model this situation is
[tex]l=31+20*x[/tex]
where [tex]l[/tex] is the number of laptops.
since x is the number of years that have passed since 2007, it can be represented like this:
[tex]x=y-2007[/tex]
where [tex]y[/tex] can be any year, so the equation to model the situation using the year:
[tex]l=31+20(y-2007)[/tex]
and this way we can find the number of laptos at the end of 2017:
[tex]y=2017[/tex]
and
[tex]l=31+20(y-2007)[/tex]
[tex]l=31+20(2017-2007)\\l=31+20(10)\\l=31+200\\l=231[/tex]
