Answer:

where
is the number of laptops, and
is the year.
in 2017: 
Step-by-step explanation:
I will define the variable
as the number of years that passed since 2007.
Since the school buys 20 lapts each year, after a number
of years, the school will have
more laptops.
and thus, since the school starts with 31 laptops, the equation to model this situation is

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

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

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

and


Answer:
equation form: x=-131/8y -31/40
Step-by-step explanation:
this is addition/elimination
The angle of elevation from the hiker to the park ranger is the same as the angle of depression from the ranger to the hiker, 29°.
The tangent function of an angle is the ratio of the opposite side (500') to the adjacent side (x) in the right triangle shown. That is
tan(29°) = 500' / x
Multiplying the equation by x/tan(29°) gives
x = 500' / tan(29°)
x ≈ 500' / 0.5543
x ≈ 902 ft
[(x**-2) y**2 .z)**2]**2 (x**-8)(y**8)(z**4)
----------------------- = -----------------------------
[x**2 . y**3]**2 (x**4) (y**6)
(y**8)(z**4) (y**2)*(z**4)
--------------------- = -------------
(x**12) (y**6) (x**12)