 
<translate> Ọ na-enweta 500 *.8 = $400 site n'ụgwọ lenses. Nke ahụ pụtara na lens ndị ahụ na-efu 500 - 400 = $100. Okpokoro ndị ahụ na-efu 200 - 50 = $150. Ya mere, ọ na-akwụ 100 + 150 = $250. Azịza ya bụ narị abụọ na iri ise. <eng> He gets 500 * .8 = $400 off the cost of lenses. That means the lenses cost 500 - 400 = $100. The frames cost 200 - 50 = $150. So he pays 100 + 150 = $250.
The answer: 250. 