<u>Answer-</u>

<u>Solution-</u>
Here, n represents the number of months and f(n) represents the number of laptops in the store after n months.
As the store had 150 laptops in the month of January or at the beginning.
So 
Every month, 20% of the laptops were sold and 10 new laptops were stocked in the store.
As 20% of laptops were sold, so 80% were in the store.
So, after one month total number of laptops in the store,


Again after one month total number of laptops in the store,


Analyzing the pattern, the recursive function f(n) will be,

Do 5.4 plus 5.8 then do 3.4w minus 1.8w and whatever you get for each is your key to the expression. So if you were to solve the answers like A you would do 7(1.6+w) and see what you would get. Obviously A isn't the answer. Sorry, this is hard to explain. But the answer is C
The scneario here expressed is an aritmetic sequence because it can be explained like this:
<span><span><span>a1</span>=35
</span><span><span>an</span>=<span>a<span>n−1</span></span>+<span>17
So all the variables can fit in and will be better explained than a geometric sequence in which you need a common ratio and that is not needed in this case</span></span></span>
Speed = distance / time
given:
distance = 225 km and time = 2.5 hours
so
speed = 225 / 2.5 = 90 km per hour
Answer:
Speed = 90 km per hour
Positive numbers is the last one