I can solve with 2 methods:
I. Because the discount is 15 % of 18 $ , the price will be (100-15=85) 85 % of 18 $
18*85/100= 15,3 $ ( the sale price)
II. The discount is 15 % of 18$
15*18/100= 2,7$ ( the discount)
then I decrease it from the regularly price
18$-2,7$=15,3 $ (the sale price)
Personally I believe the first is an easier method.
I hope you understand and you can apply this in every similary problem.
Sorry if I am wrong I am not 100% sure but I think it’s 3
Step-by-step explanation:
Given
The function is 
for
, we will check the values of
and 
Take 3 and 4

Similarly,

Thus, 
Also,
is 1 i.e. a constant value. So, the function is increasing linearly for the given interval.
Answer:

Step-by-step explanation:




