Complex sentence: In February 1987 Megadeth was the opening act on Alice Cooper's Constrictor tour, and the following month the band began its first headlining world tour in the United Kingdom.
Split into simpler sentences: In February 1987, Megadeth was added as the opening band on Alice Cooper's Constrictor tour. The following month, the band began its first world tour as a headlining act in the United Kingdom.