Caleb has 345 friends 2/3 of them are male how many are female

On a piece of paper graph f(x)=5•(0.4)^x

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

What is the axis of symmetry of the function f(x)=-(x+ 9)(x-21)