your first step is to make two equations.
we will make b=school buses and v=mini-vans
equation 1: 51b+8v=193
because each bus holds 51 students and each van holds 8 students, with a total need of seating for 193 students.
equation 2: 1b+1v=8
because the bus and the van each only need one driver and there are a total of 8 drivers available.
then you need to get rid of one of the variables in the equations, so multiply the second equation by -8
(-8)(1b+1v=8) getting a new equation of (-8b+-8v=-64)
then add the equations together
{ 51b + 8v = 193 }
{+ -8b + -8v = -64 }
{------------------------- }
{ 43b + 0v = 129 }
now you need to solve for the variable by dividing each side by 43, getting b=3
now plug that answer for b into the other equation, 1b+1v=8 so its now 3+1v=8. subtract the 3 from both sides leaving you with v=5.
now you know that you need 3 school buses and 5 mini-vans to transport 193 students with only 8 drivers
check: (plug the answers into the original equations)
51(3)+8(5) = 193 true
1(3)+1(5) = 8 true
sorry if this is hard to follow, it wasn't very easy to try to type all the equations and work them out while explaining.
Source(s):
love mathematics :)