Answer:
d
Step-by-step explanation:
Since the triangle is equilateral then the 3 sides are congruent.
Equate any pair of sides and solve for x
AC = BC , that is
10x - 5 = 6x + 3 ( subtract 6x from both sides )
4x - 5 = 3 ( add 5 to both sides )
4x = 8 ( divide both sides by 4 )
x = 2 → d