The equation of the line follows the following general structure:

Where m is the slope of the line and b is the y intercept.
Find the corresponding values in the given formula, this way:
In the given equation, m has a value of -1/2, it means the slope is -1/2.
Answer:

Step-by-step explanation:
(
)
Multiply
by each term in the parentheses.
+ 
Now, all you have to do is simplify.

Answer:
x = 72
Step-by-step explanation:
These angles are complementary so they add up to 90:
x + 18 = 90
x = 90 - 18
x = 72
Given the equation
.
When x is maximum, we have
. Hence 
The maximum temperature is 
When x is minimum, we have
. Hence 
The minimum temperature is 