John buys a new bedroom set on credit for $2760 and no interest. he pays $115 per month. what is the equation that models the money john owes?

Suppose that the equation is modeled by a linear equation:
let the amount owed by John, is y at time time,x.
the linear equation is given by:
y=mx+c
where:
m=slope
c=y-intercept
from the information:
c=$2760
m=$115
thus amount owe will be:
y=-115x+2760

40%=2/550=1/230=3/1056=14/25