An ongoing promotion at a department store gives customers 20\%20%20, percent off the portion of their bill that is over \$100$1
00dollar sign, 100. Ruby's total bill at the department store after the promotion has been applied is \$250$250dollar sign, 250. If xxx represents the amount of money Ruby would have spent on the same purchase at the department store without the promotion, which of the following equations best models the situation?
