Question

Which set of expressions are not equivalent?
1) (4a²) / 3 and (5 / 4a) * (18a / 14)
2) 6a / (12 * 2) and (1 / 2a) * (0.5a / 3.5)
3) 4a / 3.5 and (4.5a / 3a) * (7 / 2a)
4) 7a / 5 and cannot be determined