ElectricPavlov

Multiply the FIRST equation by  -2 to get

-10x -2y = -18      then add it to the SECOND equation

 10x - 7y = -18

____________

       -9y = -36      yields y = 4  

Substitute this value of y into one of the equations to find 'x'

5x+y=9

5x +4 = 9 

5x=5      x= 1 

for SURFACE area (including the ends)

Area = 2 x pi r^2  + pi x d x h 

(3/2)^(1/5) =  \(\sqrt[5]{3/2}\)

 = 1.0844717711976986

3 7/10  x  2  1/2 =

37/10  x  5/2

= (37 x 5) / (2 x 10)

185/20

= 9 5/20 = 9 1/4

Lowest common denominator would be  9

Plug in to the given eqaution and solve for 'x'

cube s = 6 x^2

150 = 6 x^2

25 = x^2

5 = x

x = 5 inches   = length of a side

From Wikipedia:

Opposite number or additive inverse of any number (n) is a number which, if added to n, results in 0, the identity element of addition. The opposite number for n is written as −n. ... You can say that the opposite number of a number, is the negative version of the positive number.

Beth age = x

Cordell = 2x

8 years ago   Cordell was  2x-8    which was 3 times (x-8)

So

2x-8 = 3(x-8)

2x-8 = 3x - 24

x=16 = Beth age     2x = Cordell's age = 2(16) = 32 y/o

You would get a NEGATIVE result...

example     3 - 8 = -5

x = number

-x = opposite of number

5(-x) + 56 = 2x

-5x +56 = 2x

56 = 7x

8 = x