How many students were surveyed? alot of points, need answers asap

The size of a certain cell is 2.5*10^-9m. another cell is 1.5*10^3 times larger. how large is the larger cell in scientific notation?

Haruka hiked several kilometers in the morning. she hiked only 66 kilometers in the afternoon, which was 25% less than she had hiked in the morning. how many kilometers did haruka hike in all?

Bobby bought 1.12 pounds of turkey at a cost of 2.50 per pound. carla bought 1.4 pounds of turkey at a cost of 2.20 per pound. who spent more and by much?