I'm confused I think it might be a one to one function I'm not sure. But I just need to know if its a function and if it is what kind.

Alake near the arctic circle is covered by a sheet of ice during the cold winter months. when spring arrives, the ice starts to melt. s(t) models the ice sheet's thickness (in meters) as a function of time tt (in weeks). s(t)=-0.25t+4

Aregression was run to determine if there is a relationship between hours of tv watched per day (x) and number of situps a person can do (y). the results of the regression were: y=ax+b a=-0.662 b=30.418 r2=0.703921 r=-0.839

Alicia puts $400 in a bank account. each year the account earns 5% simple interest. how much money will be in her bank account in six months?