What does a, b, and c equal?

The price of an item has been reduced by 30%. the original price was $30. what is the price of the item now ?

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

Joe has some money in his bank account he deposits 45$ write an expression that represents the amount of money in joe's account