Answer:
Step-by-step explanation:
14r=84, r=84/14=6, so the hourly rate is $6 an hour so
y(x)=6x
Since this is of the form y/x=k or y=kx it is directly proportional. Inverse proportion is of the form yx=k or y=k/x
Use this website: https://www.angio.net/personal/climb/speed.html

In order to be differentiable everywhere,
must first be continuous everywhere, which means the limits from either side as
must be the same and equal to
. By definition,
, and


so we need to have
.
For
to be differentiable at
, the derivative needs to be continuous at
, i.e.

We then need to have

Then

You have to make 7 into 21/3. Then change 2 1/3 into 7/3. Then divide 21/3 abd 7/3 which equals 3/3 which equals 1.
Your question is not clear, but it looks as though you want to know how Brie can make a similar sandbox with base = 8ft.
Answer:
For Brie to make a similar sandbox, he must use a base = 8ft, and height = (8/3)ft
Step-by-step explanation:
It is possible for Brie to make a similar triangular sandbox with base = 12ft and height = 4ft.
All he must ensure is that the ratio of base to height of the original sandbox is the same ratio of base to height of the one he is trying to make.
The original sandbox is 12:4
Because he wants to use a base = 8ft, the sandbox he is trying to make is 8:x
Where x is the height of the sandbox he is trying to make.
Then for these sandboxes to be similar, the ratio 12:4 = 8:x
=> 12/4 = 8/x
12x = 8 × 4
12x = 32
x = 8/3
The height must be (8/3)ft