we are given that
The box of oranges cannot exceed a mass of 200kg
so, total mass is 200kg
now, we can change into gram
1kg=1000g
so, total mass is 200kg=200*1000g=200000g
each orange has a mass of 400g
so, mass of one orange is 400g
Let's assume
total number of orange is n
so, we can use formula
total number of orange = (total mass of orange)/(mass of one orange)
so, the maximum number she can send is 500.........Answer