Question

Mary has a budget of $40 per month to spend on movies. She made a table showing the total amount of movie money she will have left after seeing the given number of movies. Number of movies 0 1 2 3
Total amount of movie money left ($) 40 29 18 7
Which equation, in standard form, represents the relationship between the number of movies, x, and the amount of movie money Mary will have left, y?

11x−y= 4011x−y= 40

11x + y = 40

x + 11y = 40

x−11y= 40

Answer 1

x=0->y=40
x=1-> y=29
x=2->y=18
x=3->y=7

Answer 2

Which one of the equation satisfies the above?

Answer 3

The first 2 equations give you for x=0, y=-40
The first 2 are no good

Answer 4

Continue like this until you find the one that meet all the 4 conditions

Answer 5

Try third choice and let me know when you come back

Answer 6

Alternative approach: find slope of data, and write the equation you need.

If we look at the data, for each additional movie watched, cash left decreases by $11. This means we have a slope of \(-11\). If we remember slope-intercept form, \[y=my+b\]where \(m\) is slope and \(b\) is y-intercept, or the value of \(y\) when \(x=0\)

plug in the value you found for \(m\) and any pair of \(x,y\) from your data to get the equation. Then rearrange it into standard form and choose the answer that matches.

Answer 7

Also, you can look at it this way:

After she sees 1 movie, she is down $11.
For each movie she watches, her budget goes down by $11.
Also, she started with $40

Amount she has left = initial amount - amount spent in x movies

y = b - mx

where m = -11, and b = the initial amount, $40