Martin, a life insurance agent, is meeting with married couple Richard and Susan to discuss the purchase of disability insurance by both of them. Richard earns $60,000 yearly, while Susan earns $36,000. After reviewing their current monthly expenses, it is established that Richard is responsible for $3,000 of their monthly expenses, while Susan is responsible for $1,500. Using an expense approach to determine Richard and Susan's disability income needs, what amount of monthly coverage should Martin recommend for each of them?