When comparing to thing with same rate, set up a proportion:
Inches/cost
13/.78=33/x
(13)(x)=(.78)(33) [cross multiplied]
13x=25.74 [simplified]
13/13x=25.74/13 [division property]
x=1.98
33 inches of wire will cost $1.98.
Rewrite the equation into slope intercept form:
8y = -5x+16
divide everything by 8 to get just y
y = -5/8x+2
the slope = -5/8
This problem already gave us the slope and y-intercept, so all that's left to do is plug those two values into slope-intercept form.
Slope-Intercept Form: y = mx + b
---m is the slope
---b is the y-intercept
y = 8/3x + 5
Hope this helps!! :)