A - Difference in tides for location C is 6.9 feet and high tide for location A is 8.2 feet.
B - Value of low tide in location D is -0.64 feet.
The table showing the difference between high and low tides.
The difference in tides for location C = 7.34 - 0.44 = 6.9
We are given, the mean of the low tides for the 4 locations is -0.54
He would be standing 5.3+2.5=7.8
so hes standing 7.8m away
Let x denote the length of the side of the garden which is covered fenced by a shed, and

be the width of the garden.
The perimeter of a rectangle is given by 2(length + width)
i.e.
which gives:

For the area to be maximum, the differentiation of A with respect to x must be equal to 0.
i.e.

Therefore, the maximum area of the garden enclosed is given by
6.5 apple per pie, is that what the question is asking?