Joann\textquotesingle s birthday in $$2020$$ was May $$10$$\textsuperscript{th}, which was Sunday. Elizabeth\textquotesingle s birthday in $$2020$$ was June $$21$$\textsuperscript{st}. What day of the week is Elizabeth\textquotesingle s birthday on? 
Overseas Competition->Knowledge Point->Word Problem Modules->Periodic Problems->Periodic Problems of Time
It passed $$31-10 + 21 = 42$$ days in total. Since $$42 \div 7 = 6$$, it was Sunday. 