A project will have one of the following time $1$ payoffs, each with the corresponding probability.

$$83$ with probability $11\%.$

$$336$ with probability $55\%.$

$$521$ otherwise.

The discount rate is $6\mathrm{.}3\%.$ Debtholders contribute $$115$ at time $0$ to finance the project. What is the promised return on the debt? Give your answer in percentage to closest $0\mathrm{.}1$ percent.