Determine the domain

Colby and jaquan are growing bacteria in an experiment in a laboratory. colby starts with 50 bacteria in his culture and the number of bacteria doubles every 2 hours. jaquan starts with 80 of a different type of bacteria that doubles every 3 hours. let x equal number of days. colbys experiment follows the model: a.) y=50*2^x b.) y=50*2^8x c.) y=50*2^12x jaquans experiment follows the model: a.)80*2^x b.)80*2^8x c.)80*2^12x

:24% of students in a class are girls. if there are less than 30 students in this class, how many students are there? how many girls are there?

How many sides does a regular polygon have if each exterior angle measure is 45 degrees explain your answer, i really don't understand this.