The best answer I believe is C
16x-32=48 /+32
16x=80/:16
X=5
Day Sis you
1 -30 20
2 0 40
3 30 60
4 60 80
5 90 100
6 120 120
So day 6.
Firstly arrange data from smaller to greater data point:
4 5 6 9 10 11 12 13 15 16
Secondly find the middle value: In our case the number of data is even, so to get the middle value we have to find the mean (average) between 10 & 11, that is 10.5. So the rank of the Median is10.5
Start finding the slope of the line

using one of the points find the intercept and the standard form

the equation of the line is