No problem definition
Also, no sweat; not to worry. There's no difficulty about this, don't concern yourself. For example, Of course I can change your tireno problem, or You want more small change? no sweat, or We'll be there in plenty of time, not to worry. The first of these colloquial terms dates from about 1960 and the second from about 1950. The third, originating in Britain in the 1930s and using not to with the sense of "don't," crossed the Atlantic in the 1970s.
You're welcome, as in Thanks for the ride, Dad.No problem. [Late 1900s]