Need to solve the basic math problem

Question

350 parcels are sent into 3 vans for delivery. The first van contains twice as many parcels as the second van. The third van contains twice as many parcels as the first van. How many parcels are in each van?

Answer 1

F=2S, T=2F

F+S+T = 350

F + F/2 + 2F = 350

7F/2 = 350

F/2 = 50

F = 100 = parcels in 1st van

S= 50 = parcels in 2nd van

T = 200 = parcels in 3rd van