Answer :
[tex]x-number\ of\ day\ ticket\\120-x-number\ of\ night\ ticket\\\\5x+7(120-x)=740\\5x+840-7x=740\\5x-7x=740-840\\-2x=-100\ \ \ \ \ \ \ \ \ |:-2\\x=50\\\\120-50=70\\\\There\ where\ sold\ 50\ rickets\ during\ the\ day[/tex]
50 tickets, but the $740 part makes the question impossible to answer. I see where you were going with it though.