Answer:

Step-by-step explanation:
To add two fractions we need a common denominator. Just by looking at the two, there are no common factors. This means the denominator would be the product of the two: 4x(x-8). In order to obtain this, we multiply the first fraction by (x-8)/(x-8) - 1, and the second by 4x/4x - 1:

We can use the distributive property to simplify:

The sum of the two is:

The volume of a sphere is: 4/3 (pi) (radius cubed.) You would use that formula to solve for the volume.
Step-by-step explanation:
a.
simply add both equations
x + y = 2
-3x - y = 5
----------------
-2x + 0 = 7
x = -7/2
x + y = 2
-7/2 + y = 2
y = 2 + 7/2 = 4/2 + 7/2 = 11/2
b.
1/2 x + 2y = -13
x - 4y = 8
first multiply the first equating by 2
x + 4y = -26
x - 4y = 8
--------------------
2x + 0 = -18
x = -18/2 = -9
x - 4y = 8
-9 - 4y = 8
-4y = 17
y = -17/4