Given the variables taxablepurchases and taxfreepurchases (already declared and assigned values), write an expression corresponding to the total amount purchased.

Tax is a portion of value that is added to purchases (while some of the purchases are not tax-imposed). Taxes are imposed so that the money obtained from the additional payment goes to the government to be used for infrastructure/education/govt works. The total amount of purchased say if one is making purchases is expressed as total amount = taxable purchases + taxfree purchases