We are asked to determine the area of the given figure. To do that we will divide the figure into a square and a triangle. The area of the square is the product of its dimension, therefore, the area is:

The area of the triangle is given by the following formula:

Where "b" is the base and "h" is its height. Replacing the values:

The total area is the sum of both areas:

replacing the areas:
Hi!
So for this problem, we're given the y-coordinate and we can plug that in for y in the equation. So let's do that
-1 = -3/5x - 7
6 = -3/5x
30 = -3x
-10 = x
The missing coordinate would be x, assuming that the equation was y = (-3/5)x - 7
The 6 terms of the series are
... 15, 14, 13, 12, 11, 10
The sum of them is 75.
_____
You could make use of the formula for the sum of the terms, or you could work out the sum from the given expression. It is easier just to list the terms and and them up.
Answer:
the radius is 5 cubic meters