I ate lunch every day of my $$12$$-week summer break. I ate lunch out-doors only on every Saturday, Sunday, and Tuesday. I ate lunch in-doors ondays. 
Overseas Competition->Knowledge Point->Word Problem Modules->Unitary Method Problems->Finding the Total Value using Unitary Method
I ate lunch every day of my $$12$$-week summer break. I ate lunch out-doors only on every Saturday, Sunday, and Tuesday. I ate lunch in-doors $$4$$ days each week. In $$12$$ weeks, that\textquotesingle s $$12\times 4=48$$ days. 