Question

Katie's favorite deli has a salad bar where she can make her own salad. She has to pay $1 for the container and $3 per pound for the salad.

Write an equation that shows how the total cost, y, depends on weight of the salad in pounds, x.
Do not include dollar signs in the equation

Answer 1

Answer: y = 3x + 1

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) =
`\frac{y_(2)-y_(1)}{x_(2)-{x_1}}`, we can get the equation m =
`(7-4)/(2-1)`, thus telling us that m =
`(3)/(1)`, 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

Answer 2

y = 3x + 1

Explanation: