Which expression can you substitute in the indicated equation to solve 3x − y = 5, x + 2y = 4 ?

A 2y − 4 for x in 3x − y = 5
B 3x − 5 for y in x + 2y = 4
C 3x − 5 for y in 3x − y = 5
D 4 − x for y in 3x − y = 5