Answer:
4
Explanation:
5n²- 40n + 80=0
(divide the equation by 5)
n²- 8n + 16=0
(which number multiplied together gives us 16?)
(therefore here we are required to find the factors of 16)
(then when we find these factors we should take the ones when added gives us -8)
factors:
1 16
2 8
4 4
-4 x -4 gives us as product 16 and their sum is -8
n²-8n+16=o
(n-4)(n-4)=0
n-4=0
n=4