How many seats are available for students on the buses,350,340,72,68

There will be 340 spaces for students to sit in. You would do 70 x 50 which gets you 350 and then do 2 x 5 which is 10. Then you do 350 - 10 which gets you 340.

Part I:
total number of seats for students = x
total number of seats per bus = 70
total number of seats Not occupied by students per bus = 2 (which means you must subtract)

x = 70 - 2
x = 68 seats for students

Part II:
total number of buses = 5
total number of seats for students per bus = 68
x = how many seats for students all together (add or multiply to get answer)

× = 5 x 68
x = 340 seats for students all together