Solution
Part 3
For this case we have 6 different terms
Part 4
We can do the following:

Part 5
And we can simplify on this way:

0.5 x 4 = 2 feet / 2 feet in 4 seconds
15 - 2 = 13
New depth: 13 feet
0.4 x 3 = 1.2 feet / 1.2 feet in 3 seconds
13 - 1.2 = 11.8
New depth: 11.8 feet
3.2w/8 l=x w/5 l
X= 5• 3.2/8= 16/8=2 centimeters
That creates the number 82,190