Answer :
x=cars
y=buses
x+y=7 vehicles
5x+45y= 195 students
-5x-5y=-35
+5x+45y=195
------------
40y=160
--- ---
40 40
y=4
x+4=7
x=3
They took 4 buses and 3 cars
y=buses
x+y=7 vehicles
5x+45y= 195 students
-5x-5y=-35
+5x+45y=195
------------
40y=160
--- ---
40 40
y=4
x+4=7
x=3
They took 4 buses and 3 cars