So first step would be to find the percent Keith got off for his jeans. To do that subtract 130-91 to get a difference of 39, then multiply 39 by 100 which is 3,900 and then divide by 130 which will give you 30. Which means Keith got 30% off his jeans. So, to find how much his shirt cost if he got 30% off you would multiply the original price, 23 by 0.3 or 30 percent and you get 6.9 then subtract 23-6.9 to get 16.1. So Keith bought his shirt for $16.10.