Lets say that the number of students in the van are represented by X and the number of students in the bus are represented by Y.
You would have the following equations:
high school A: 2x+8y=360
high school B: 6x+y=114
Now we can use the method of substitution to solve this system of equations. So I will solve the second equation for y and plug it into the first equation.
The second equation you would have to subtract 6x from both sides in order to get y by itself. So then you are left with
y=114-6x
Now we plug this into the first equation (2x+8y=360)
So you would get this equation: 2x+8(114-6x)=360
Distribute the 8 and you get: 2x+912-48x=360
Now combine the like terms (add the terms with the x's) and you get: -46x+912=360
Subtract 912 from both sides and you get: -46x=-552
Divide both sides by 46 and you get x=12 (this is the number of students in each van).
Now we can plug this value into one of the initial equations: I will use the equation for high school B (6x+y=114)
6*12+y=114
72+y=114, now subtract 72 from both sides and you get y=42 (this is the number of students in each bus)