Can somebody link some videos (or other stuff) for studying expressions and equations like the math with the letters? I'm struggling and I defiantly need to study but I can't find anything. :)

Aproduction manager test 10 toothbrushes and finds that their mean lifetime is 450 hours. she then design sales package of this type of toothbrush. it states that the customers can expect the toothbrush to last approximately 460 hours. this is an example of what phase of inferential statistics

Find the domain and range of the following function f(x) = 51x - 21+ 4

Jayne is studying urban planning and finds that her town is decreasing in population by 3% each year. the population of her town is changing by a constant rate. true or false?