The population of a developing city increases by 30% annually. If the population was 12,000 in 1990. In what year is the population triple its original value?

Last month, leonhard euler's watch kiosk at the mall had total sales of $9,489. merchandise totaling $225 was returned. the goods that were sold cost leonhard euler's $5,481. operating expenses for the moth were $992. what was the gross profit on sales?