CPhill

I believe you made a slight sign error, hoiuu.....check this out

Slope =   [ -2 - 6 ]  / [  2 - - 2 ]   =   -8/4    = -2

So......using  ( 2, -2)  we have

( y - [-2 ] )  =  -2 ( x -  2 )  =

( y + 2) =  -2 ( x -  2)

We have    7 + 5 + 9   =   21 equal parts

And B's donation was  5 of these

So

(5/21) * 42000   =  $10000 

Slope  =  [ -1 - 5 ] /    [  -2 - 6 ]  =  -6/-8 =  3/4

Using   (6,5)  we have

( y - 5)  =  (3/4) ( x - 6) 

P. S.   ....I'm glad to see that you are trying to work toward the answers instead of just  accepting them blindly...!!!

Put 15  into the original function and we get 0  back

So

(15, 0)  is on the original function

So....0  should return 15 in your proposed inverse....so

3(0)  +  15  =  15  ....correct  !!!

Note...this isn't foolproof....but if given a list of proposed inverses...it should test out 

There is a "foolproof" method  [ if you are interested.... ]

Correct  !!!!

Note....here's how you can check your solution

Put  a value  in the first equation...I'll choose  3...  and we get - (4/3) * 3  + 2  =  -4+ 2  =  -2

So...the point ( 3, -2)  is on the graph

The inverse "reverses" the   coordinates....so the point (-2, 3) should be on the inverse graph

So...putting -2 into your inverse and we get

-(3/4) (-2)  +  3/2  =

6/4 + 3/2  =

3/2 + 3/2  =

3  !!!!!

So   ( -2, 3)  shows that your inverse solution is correct  !!!!

Good Job  !!!!

We have two  equations, here

x - 500  = 8           and                       - ( x - 500)  =  8

Add 500 to both sides                          Simplify

x  =  508                                              -x + 500  = 8

                                          Add x to both sides. subtract 8 from both sides

                                                                   492  = x

So   [ min. max ]   =   [ 492, 508 ]  ⇒  "C"

We don't need much math here, hoiuu

Total cost  =   Variable Cost  + Fixed Cost

The Variable Cost  =  25 times "x" number of days  rented   = 25x

The Fixed Cost  = 50    [ this amount is paid no matter what ]

So.letting the Total Cost  = y

y  = 25x + 50

Does this make sense  ???

Slope  =   [ 40 - 55 ] / [ 3 - 0 ]  =    -15 /  3  = - 5

Equation of line using  (0 , 55)

y =  -5x + 55     add 5x to both sides

5x + y  =  55

Correct. hoiuu  !!!!!!

y  =  -3x  + 5      first....we want to get x by itself

y - 5  =  3x        divide both sides by 3

[ y - 5 ] / 3  = x

"Swap"  x and y and for, y write   f^-1(x)

[ x - 5 ] / 3  =  y

[x - 5 ] / 3  =  f^-1(x)   =  (1/3)x  - 5/3

Based on these steps.....can you do the second one, Jenny ????