Answer :
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.
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.