Step-by-step explanation:
Aight, lemme give it a shot
so ya got 50 boxes and each box weighs 30 kg
so in total ya go 50×30=1500kg weight
and on the other hand ya are allowed to carry the maximum of 450 kg
now check it
1500÷450=3.3
So
450×3=1320kg
the van can be full for three drives and
1500–1320=150kg
and it has to be driven to the shop with ⅓ of maximum weight only once
so it'll be 4 drives