127.1 g Cu combines completely with 32.1 g S to form a compound. What is the percent composition of this compound?

A. 20% Cu; 80% S
B. 50% Cu; 50% S
C. 80% Cu; 20% S
D. 127% Cu; 32% S
I say A

I say c

127.1 / (127.1+32.1) = %Cu

32.1 / (127.1 += 32.1) = %S