one person: 4 trees
5 people: 20 trees
x = number of people working
y= number of trees planted
So, each people plants 4 trees:
1 person =4 trees:
5 people 20 trees = 20/5 = 4 trees per person
Greta is correct, because:
4 = 4 x1 ( one person 4 trees)
and 20 = 4 x 5 ( 5 people 20 trees)