Answer:
60
Step-by-step explanation:
The quadratic function tells me that the graph has a vertice at (-40, 60).
So the minimum number of mango yield per year is 60.
Howevery, i believe that there is a mistake in the question;
The quadratic function should be [tex]y = (x-40)^2 +60[/tex]
Because we cannot have negative number of mango tree.
