Liam attended a Singapore Maths Olympaid (SMO). Liam answered all $30$ questions. For each correct answer, Liam will get $5$ marks. However, for each wrong answer, Liam will deduct $1$ mark. If Liam scored $90$ marks in total, how many questions did Liam answer correctly? 
Overseas Competition->Knowledge Point->Word Problem Modules->Chicken-Rabbit Problems