Point-slope form: y-y1 = m(x-x1)
Standard form: ax + by = c
Slope-intercept form: y = mx+b
Start by finding the slope. We know it is negative since the line is decreasing. The slope is -4/3.
To create point-slope form, we need to get one point from the graph. Let's use (3,0).

To create slope-intercept form, we need the slope and the y-intercept. The y-intercept is the point where our equation crosses the y-axis. For this equation, it is 4.

To get standard form, solve the equation in terms of C.
Point-slope form: y = -4/3(x-3)
Slope-intercept form: y = -4/3x + 4
Standard form: 4/3x + y = 4
Completing the square follows the principle of taking

and converting it into

where d is the 'correctional number' as I like to call it - i.e. the number that converts the expanded bracket into the +c, since the expanded bracket will give us

.
In this case, 2/2=1 so we have the first part:

.
Expanding this gives us

. We need c to be 9, so we can just add 8.
Putting this together:

Now we can solve it more easily.
Rearranging:
Answer:
plain = $10.50
pepperoni = $12.50
Step-by-step explanation:
x = pepperoni
y = plain
3x + 2y = 58.5
2x + 4y = 67
using substitution method, I multiplied the first system by -2 to get:
-6x - 4y = -117
+ 2x + 4y = 67
-4x = -50
x = $12.50
2(12.5) + 4y = 67
25 + 4y = 67
4y = 42
y = $10.50
Answer:
2
Step-by-step explanation: