A 12-oz cup of regular coffee at Starbucks has 13 times the amount of caffeine found in the same-sized serving of decaffeinated coffee. Together they contain 280 mg of caffeine. How much caffeine is in each type of coffee?

Respuesta :

If the decaffeinated is x, the regular coffee would be 13*x = 13x

They both total 280 mg.

x + 13x = 280

14x + 280

x = 280/14

x = 20 mg

x, and 13x              x = 20,  13x = 13*20 = 260

Decaffeinated has 20 mg and the regular coffee in Starbucks has 260 mg.