Answer :

[tex]n-an\ unknown\ number\\14\cdot n=14n-the\ product\ of\ 14\ and\ an\ unknown\ number\\34\ less\ than...-subtract\ 34\\\\so,\ we\ have\ an\ equation:\\\\14n-34=78\ \ \ \ |add\ 34\ to\ both\ sides\\14n=112\ \ \ \ |divide\ both\ sides\ by\ 14\\\boxed{n=8}[/tex]