Adding a 12% percent profit?

This is regarding a portion of a graded homework ignment. I was checking to see why I got it wrong. Your have $2,675,191.57. Your are supposed to add a profit of 12% to that' number. I multiplied that number by 1.12 and got $2,996,214.56. The book answer devided the number by .88 and got $3,039,990.42. I subsequently missed the problem. I guess im confused as to why the answers are different for one thing and for another what is the proper way to figure out the 12% percent profit? Thanks for any help on this.