Earned $5 per hour for h hours

Can someone me my sister? she is in third grade. 50 points and brainlist! ones that are not answered. plz and thx!

Expresa commuter train leaves downtown sation and travels at a average speed of 55 miles per hour towards the north side sation, which is 50miles away. thirty minutes later, express commuter train #7 leaves north side and travels at a average speed of 35miles per hour towards downtown sation. at the moment the two trains pass each other, how far(in miles) is train #12 from the downtown sation and how long(in minutes) has the #12 train been traveling

What is the simplified form of (3.25x10^3)(7.8x10^6) written in scientific notation?