13. \"Partial disability" means that the insured is unable to perform a certain level of regular duties. Assume a person was making $100,000 of annual income and was entitled to a disability benefit of $6500 per month. Where the disability policy is defined by the loss of income, how much benefit should they receive monthly if, after an accident, they were only able to return to work 2 days per week and had to suffer a reduction in salary accordingly