Mr Lim fill $$27$$ ℓ\textbf{~}of petrol in his motorcycle in week $$1$$, $$25$$ ℓ\textbf{~}in week $$2$$ and $$30$$ ℓ\textbf{~}in week $$3$$. How many litres of petrol did he fill in his motorcycle altogether?  He fill~\uline{~~~~~~~~~~}~ℓ ~of petrol in his motorcycle altogether. 
Overseas Competition->Knowledge Point->Word Problem Modules->Applying Addition and Subtraction->Simple Addition and Subtraction