$25 times 0.65 = $16.25 & then you do $25 - $16.25 which equals $8.75. So you save $8.75 by buying the pants on sale.
You could say:
y = 4x + 10
John runs 10 miles a week, after every month he adds 4 miles.
y = 3x + 15
Mary runs 15 miles a week, after every month she adds 3 miles.
'y' would represent the total miles and 'x' would represent the number of months.
It also goes from linear too, I don’t know what else sorry