Answer:
Part 1) The number of classes must be greater than 20
Part 2) see the explanation
Part 3)

Part 4)

Part 5) The equation that can be used is
and the cost of one print is

Part 6) The number of classes must be greater than 30
Explanation:
Part 1) we know that
The linear equation in slope intercept form is equal to

where
m is the slope or unit rate
b is the y-intercept or initial value
Let
y ----> the total cost
x ----> the number of classes
we have
Members
The slope is

The y-intercept is

so
----> equation A
Non-Members
The slope is

so
----> equation B
To find out how many classes would a member have to take to save money compared to taking classes as a non-member, solve the following inequality

Solve for x
subtract 10 x both sides


Divide by 5 both sides

Rewrite

therefore
The number of classes must be greater than 20
Part 2) we have
The sum of 8 and 3 times a number is 23.
Let
x ----> the number
Remember that
3 times a number is the same that multiply 3 by the number ----> 3x
so
The sum of 8 and 3 times a number is 23 is the same that

solve for x
subtract 8 both sides


Divide by 3 both sides

Part 3) we know that
The linear equation in slope intercept form is equal to

where
m is the slope or unit rate
b is the y-intercept or initial value
Let
y ----> the total cost of renting a car for one day
x ----> the number of miles
we have
The slope is

The y-intercept is

so

For x=78 miles
substitute in the linear equation and solve for y


Part 4) Let
x ----> Alice's normal hourly rate
we know that
40 hours multiplied by her normal hourly rate plus 10 hours (50 h-40 h) multiplied by 1.5 times her normal hourly rate must be equal to $660
so
The linear equation that represent this situation is

solve for x


Divide by 55 both sides

Part 5) Let
x ----> the cost of one print
we know that
The cost of one print multiplied by 27 prints must be equal to $242.73
so
The linear equation is equal to

solve for x
Divide by 27 both sides

Part 6) we know that
The linear equation in slope intercept form is equal to

where
m is the slope or unit rate
b is the y-intercept or initial value
Let
y ----> the total cost
x ----> the number of classes
we have
Members
The slope is

The y-intercept is

so
----> equation A
Non-Members
The slope is

so
----> equation B
To find out how many classes would a member have to take to save money compared to taking classes as a non-member, solve the following inequality

Solve for x
subtract 7x both sides


Divide by 4 both sides

Rewrite

therefore
The number of classes must be greater than 30