Each van carries 18 students and each bus carries 59 students.
Let v = the number of students a van carries
Let b = the number of students a bus carries
For the string orchestra, we know that they have 372 students and they filled 1 van and 6 buses, so:
for the bands, we know that they had 390 students and they filled 2 vans and 6 buses, so:
To solve for one of the variables, let's subtract one equation from the other - either way will work, but in this case, I'm subtracting equation 1 from equation 2 so we don't have to deal with negative numbers.
We can now substitute this into either of the original equations and solve for b:
If you want to check your answer, you can substitute the numbers you got into the equation that you didn't use to solve for the last step:
This statement is true, which means our answer is correct!