Just substitute in values into the equation corresponding to the x,y:
To solve for a missing y value, substitute the corresponding x value, so 0, 2.33, and 6.25.
To solve for x, set the equation equal to the x and solve.
x's:
0
.25
2.33
4.5
6.25
y's:
5
5.75
14.99
18.5
23.75
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By scenario, you could make that equation 3x + 5 the rental time of a very cheap carper cleaner service. They charge 5 dollars as the static fee, and 3 dollars per hour