Each angle on a triangle pertains to the opposite side
so let’s start by solving the equations:
6 + 4 = 10
2(6) - 3 = 9
3(6) - 10 = 8
then order then look at what each of the sides is opposite to:
10 = A
9 = B
8 = C
so from smallest to largest the angles are C, B, A