How do you write 715.7 in scientific notation

Samantha swam upstream for some distance in one hour. she then swam downstream the same river for the same distance in only 12 minutes. if the river flows at 4 mph, how fast can samantha swim in still water?

Henry is an avid reader, he devours 90 pages in half an hour how many pages has henry read per minute?

Express in the simplest form: (x^2+9x+14/x^2-49) / (3x+6/x^2+x-56)