Answer :
Answer: y = 3x + 1
Step-by-step explanation:
Following the y = mx + b theory, we can find the equation (see attached image) by plugging in two points of the hypothetical graph.
For one pound of salad, Katie will pay $4 ($3 for the salad, $1 for the container). Thus, the first point will be (1,4). For two pounds, Katie will pay $7. Thus, the second point will be (2,7).
Knowing that m (slope) = [tex]\frac{y_{2}-y_{1}}{x_{2}-{x_1}}[/tex], we can get the equation m = [tex]\frac{7-4}{2-1}[/tex], thus telling us that m = [tex]\frac{3}{1}[/tex], or 3. Plug in 3 for m, and you get y = 3x + b.
To solve for b, lets' use the second point (2,7). Plug in the coordinates and you get 7 = 3(2) + b, or 7 = 6 + b. Subtract 6 from both sides and you get b = 1.
Plug in 1 for b and you end up with y = 3x + 1
