You lost $100 because 300-200 is 100.
Slope = 1
y-intercept = -3, which can be expressed as (0,-3).
y - y_1 = m(x - x_1)
y -(-3) = 1(x - 0)
y + 3 = x
The slope-intercept form is
y = x - 3.
The standard form is Ax + By = C.
y = x - 3
3 = x - y
Done.
I am unsure about the very last problem but I can help with the first two
1) (y+1)+4
If we combine the numbers 1 and 4, we get +5 and can isolate the numbers from the variable.
This would give us

2) (6*r)*7
remember that we do not have to explicitly state 6*r
Instead, we can write it as 6r
this helps us get rid of the parentheses
now we can write it as

I hope this helps!:)
Answer:
The range is [0,37.5]
Step-by-step explanation:
We start by writing the equation that links x and y
From the question;
y = 7.5x
Now, she has enough material to make 5 only
When we talk of range, we are referring to the values on the y-axis
So the lowest y value is 0
and since the highest number of bracelets is 5;
The total cost of the 5 is 7.5(5) = 37.5
So the range is [0,37.5]