Answer:
x = 10
Step-by-step explanation:
Use Pythagorean theorem to find the value of x
Focus only on one half of the triangle
if we slice the triangle in half, we get a right angle triangle
the base will now be 12/2 = 6
Pythagorean theorem says that 
plug 6 as a and 8 as b.
this should give you 100
now take the square root to find c (which equals x)
Ta-da!
Answer:
The first one. Top left.
Step-by-step explanation:
The top right one makes a triangular prism.
I don't even know if the bottom right is even a thing.
The bottom left is a cube.
Answer:
1/4.(-96)=2x-3
-1/4.96=2x-3
-24=2x-3
-2x-24=-3
-2x=-3+24
-2x=21
x=-21/2
Step-by-step explanation: