what expression represents an equilateral triangle if all of the sides measure (6x - 6.3) as a sum?

a) 2x + 2x + 2x - 2.1
b) x - 2.1 + x - 2.1 + x - 2.1
c) 2x - 2.1 + 2x - 2.1 + 2x - 2.1
d) 2x - 2.1 + 2x - 2.1 + 2x - 2.1 + 2x - 2.1