I’m thinking your r in the first equation is actually an x.
X + 2(2x -4) =10
X +4x -8 =10
5x = 18
2 sqrt3 + 3 sqrt3
= 5 sqrt3
Since this contains the irrational sqrt3 it is irrational
ANSWER
The product is

EXPLANATION
To find the product of

and

means we should multiply the two fractions.
We multiply to obtain,


Cancel the common factors:

Now, multiply the numerators separately and the denominators too separately.

This simplifies to,

U=2x+3, x=u/2-3/2
u^2+8u+11=0
u1=(-8+sqrt(64-44))/2=-4+sqrt(5)
u2=-4-sqrt(5)
x1=u1/2-3/2=-7/2+sqrt(5)/2
x2=u2-3/2=-7/2-sqrt(5)/2
Answer:
Area will be 2(lb + bh + hl)
So 2*(12*9 + 9*4 + 4*12)
384 sqft