Can someone help me ):

Tina practice piano for 15 hours last month and 45 hours this month use multiplication to write a statement comparing me i was tina practice during the two months use addition to write a statement comparing the hours tina practice during the two months

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?

In the xy-plane, if the parabola with equation passes through the point (-1, -1), which of the following must be true?