b = no. of buses
v = no. of vans
b + v less than or equal to 8 ( there are only 8 drivers, but don't have to use them all)
51b + 8v greater than or equal to 193 (the number of seats must be at least 193 but there can be spares)
So these are the inequalities to solve. I did start doing a linear programming graph but the second inequality is horrible so I hope you don't need to actually solve them.