How do I make 12 go into 688?

Volume of cylinder with a radius of 8cm and height of 25 cm

Evaluate the expression for the given value of the variable. 5×(h+3) for h=7

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