Ivan\textquotesingle s average score in five assignments is $80$. Billy\textquotesingle s average score is $89$ for the first four assignments. If Billy wants to score $10$ more marks than Ivan in the overall average score, find the score he needs in the fifth assignment to achieve this goal. 
Overseas Competition->Knowledge Point->Counting Modules->Statistics and Probability Overseas Competition->Knowledge Point->Word Problem Modules->Average Problems ->Questions Involving Average->Questions Involving Average (ordinary type)