A class of 195 students went on a field trip they took 7 cars and some cars and some buses find of cars and the numbers of busses they took if each other holds 5 students and each bus hold 45 students

Call the buses B and the cars C:

B + C = 7 [7 total vehicles]

45B + 5C = 195 [at 45 per bus and 5 per car, there were 195 students]

Use the first equation to express C in terms of B by subtracting B from both sides:

B + C = 7 becomes C = 7 - B

Substitute 7 - B for C in the second equation:

45B + 5 (7 - B) = 195

Multiply out:

45B + 35 - 5B = 195

Simplify and subtract 35 from both sides:

40B = 160

Divide both sides by 40:

B = 4

There were 4 buses and 3 cars used