Elena agrees to finish a knitting project for a friend. The graph shows the number of rows Elena completes compared to the amount of time spent knitting.

Assuming she worked at a constant rate, how many rows had been completed before Elena started working?
12
14
15
19

Question

Elena agrees to finish a knitting project for a friend. The graph shows the number of rows Elena completes compared to the amount of time spent knitting.

Assuming she worked at a constant rate, how many rows had been completed before Elena started working?
12
14
15
19

Vocaloid · Answer

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Vocaloid · Answer

@dude would you mind taking a look at this when you get a chance

dude · Answer

Well, you have to find the equation of the line for the points given [They told you this was a linear function as they mentioned it was at a constant rate]

y=mx+b

To find m, use $\dfrac{y_2-y_1}{x_2-x_1}$ [Choose any two points]

I would recommend using (14, 19) ->($x_1,y_1$) and (20, 22) ->($x_2,y_2$)

$\dfrac{22-19}{20-14}=\dfrac{3}{6}=\dfrac{1}{2}$

We have $y=\dfrac12x+b$

Now, we can substitute a point they gave us into x and y to solve for b (which is the value we really want)
[I used (20,22) here but you can use any other point]

$22=\dfrac12(20)+b$

Solve for b and that should be your starting amount

b = y-intercept = starting point