In order to determine the constant of proportionality by comparing minutes to day, you simply calculate the quotinent between any pair of data, in the given table.
If you for example use the following data:
Day = 4
Minutes = 24
for the constant of proportionality you obtain:
k = Minutes/Day = 24/4 and you simplify
k = 6/1
Hence, the constant of proportionality is 6/1