I think the answer would be 25 feet
The formula for volume of a sphere is 4/3pi(radius)^3
So 4/3(3.14 - better to use the pi button on your calculator)(4 cubed)
Punch into calculator (And I mean PUNCH that thing)
Volume = 268.08 in.^3. Divide this by 2.5 = 107.23 seconds.
I am pretty sure it's 44 degrees.
Y has a coefficient of 1 in the first equation, so it is easiest to use that one to write an expression for y.
... y = 20 - 2x . . . . . subtract 2x
Now, this expression can be substituted for y in the second equation.
Then, using the expression for y, we find its value
... y = 20 -2·7 = 6
The solution of the equations is (x, y) = (7, 6).