In a developing country, the growth rate of capital is 9% per hour of work and the growth rate of technology is 6%. Use the Rule of 72 to estimate how many years it will take the developing country's income to double. (Round your answer to the nearest tenth of a year.)

In a developing country, the growth rate of capital is 9% per hour of work and the growth rate of technology is 6%. Use the Rule of 72 to estimate how many years it will take the developing country's income to double. (Round your answer to the nearest tenth of a year.)