Need help ASAP doing the test now …….

Janet drove 300 miles in 4.5 hours. write an equation to find the rate at which she was traveling

Long division setup showing an incomplete calculation. 12 is in the divisor, 6839 is in the dividend, and 5 hundreds and 6 tens is written in the quotient. 6000 is subtracted from 6839 to give 839. an unknown value represented by a box is being subtracted from 839. what number should be placed in the box to complete the division calculation?

Miguel has 334 baseball cards and 278 football cards. he says, i have 612 cards in all. is that reasonable? explain using the words round and estimate.