Respuesta :
Your classmate is correct because 300-120=180 180/120=1.5 1.5 converted tp a percent is 150%
To do the math, you take the price they bought it for, (120) and multiply by the the markup price this a decimal. (120 • 1.50) which gets you 180. You then add 120 and 180. If you get 300, your classmate is correct. If you don't, your classmate is wrong. :)