Write each of the following products in exponential form: `a\ x\ a\ x\ a\ x\ a\ x .15\ t i m e s` `8\ x\ b\ x\ b\ x\ b\ x\ a\ x\ a\ x\ a\ x\ a` `5\ x\ a\ x\ a\ x\ a\ x\ b\ x\ b\ x\ c\ x\ c\ x\ c` `7\ x\ a\ x\ a\ x\ a 8\ t i m e s\ \ x\ b\ x\ b\ x\ b\ x .5\ t i m e s` `4\ x\ a\ x\ a\ x\ . . . .\ 5` times `x\ b\ x\ b\ x\ b\ . . . . .` 12 times `\ x\ c\ x\ c .15\ t i m e s`