Situations

Budget Constraint Line

1) Never Using Coupons

P x ( 1 + τ + t + τ t ) X + P y Y = M

2) Using Coupons

P x ( 1 ϕ + τ + t + τ t ) X + P y Y = M

3) Coupons Unavailable after Being Available

P x ( 1 + τ + t + τ t ) X + P y Y = M Ω