Ron's income is $50,000 and mary's income is $150,000. both pay 15% of their income in taxes. which tax structure is this? regressive proportional progressive discretionary

This tax structure called proportional. The proportional tax structure or system is a tax structure where the government asses a same tax rate to the taxpayer ignoring the taxpayer wealth or income whether he/she has a high or low income. This kind of system made to create an equality between marginal tax rate and average tax rate paid.