[Video] Q17: If the relationship between the total cost, y, of buying the materials and renting the tools at store c and the number of days, x, for which the tools are rented is graphed in the xy-plane, what does the slope of the line represent?

Explanation for Question 17 From the Math (Calc) Section on the Official Sat Practice Test 4

So now here in number 17, we're looking at the relationship between cost Y 2 buying materials at store C. 3 Um, and we need to know what this, the slope of the line represent, 4 right? So let's remember what that equation was. 5 Y is equal to M plus w plus K times X, 6 Y is equal to M plus w plus K all times X. 7 And we should know, right from general form of a line Y intercept form, 8 Y equals MX plus B, that what, 9 what is attached to the X is our slope. 10 So in this case, what should what's attached to that? Two RX is the 11 w plus K term, right? 12 So it's not the total cost of the project. 13 That's not going to be our slope, right? 14 Because our Y um, 15 our Y points are going to be, our slope are going to be the 16 total cost of our projects. 17 Um, but our slope is really just determined by the wheelbarrow and by the 18 mixer. Now, our materials are just M right, 19 which is just a normal number. They're not attached to any variable. 20 So our materials are actually kind of like our Y intercept in this case, 21 right? They're just a normal number like B, M C says 22 the total daily cost of the project. Again, 23 that's not going to be it because the daily cost, um, 24 appears to be just, you know, 25 it could include materials as well. So it's not going to be the total 26 daily cost because total daily cost should include materials. 27 And so if we're looking at D right, the total daily rental costs of 28 the tools, let's go back up and, 29 and make sure we know exactly what the tools are. 30 Um, right. So renting the tools right here 31 is the w in the K. So this is what we want here. 32 Our best answer is going to be D because these, 33 the only answer choice that specifically refers to our w and K variables, 34 which are in fact, our slope, because they are attached to the extreme of 35 our equation.