Please help 10 pts!!

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

If (x-2) 2= 49, then x could be a. -9 b. -7 c.- 2 d. 5 e.9

The candy store is having a 30% off sale. emma is going to buy $7.50 worth of candy.how much will she pay after the discount