Complex sentence: This version used used Aerozine 50 (a 50-50 mix of UDMH and hydrazine) as fuel and nitrogen tetroxide (N 2 O 4) as oxidizer, rather than the previous nitric acid/UDMH.
Split into simpler sentences: This version used used Aerozine 50 as fuel and nitrogen tetroxide (N 2 O 4) as oxidizer. It burned N2O4 (nitrogen tetroxide) and Aerozine 50 (a 50-50 mix of UDMH and hydrazine) rather than the previous nitric acid/UDMH.