Abilliards triangle is equilateral. what is its perimeter?
one side is (2x+1) in and the other is (4x - 9 1/4) in.

Equilateral triangle: is a triangle in which all tree sides are equal.

therefore:
one side (2x+1)in =other side (4x-9 1/4)in
9 1/4=9+1/4 =(36+1)/4=37/4
we have this equation:
2x+1=4x-37/4
lowest common multiple=4
8x+4=16x-37
8x-16x=-37-4
-8x=-41
x=-41/-8
x=5.125

therefore:
lenght of the side=(2x+1)=(4x- 9 1/4)
2x+1=2(5.125)+1=11.25

Perimeter of a equilateral triangle=3(lenght of the side)
Perimeter of this equlateral triangle=3(11.25)=33.75

the perimeter of this equilateral triangle is 33.75 in.