You will need to set up and solve 2 equations:
A) 3 Vans + 10 Buses = 379
B) 14Vans + 13 Buses = 624
Multiply equation A by -14
A) -42 Vans -140 Buses = -5,306 then Multiply equation B by 3
B) 42 Vans + 39 Buses = 1,872
Adding BOTH equations
-101 Buses = -3,434
Each Bus holds 34 Students
Putting this into equation A
A) 3 Vans + 10 Buses = 379
A) 3 Vans + 10 * 34 = 379
A) 3 Vans +340 = 379
A) 3 Vans = 39
Each van = 13 students