1.jack  did good in Maths than in English
=> Jack did better in Maths than in English.
2,this is the worse performance ive ever seen
=> This is the worst performance I’ve ever seen.
3.laura came back soonest than we did
=> Laura came back sooner than we did.
4.your car is a bit slow than mine 
=> Your car is a bit slower than mine.
5.july is the hotter month of the year
=> July is the hottest month of the year.