galaxy a has 8x10 stars. galaxy b has 6x10 stars. choose which galaxy has more stars. then fill in the blank with a number written in standard notation

Answer: 750 times more stars.
Step-by-step explanation:
You already know the answer (Galaxy B is quite obviously larger) but the amount of times larger is dependent on the value you get when you divide;
6 billion by 8 million (6,000,000,000/8,000,000)
...which is 750.