Jennifer had some stamps. She gave 30 stamps to Keith and 2/7 of the remaining stamps to her sister. She had 270 stamps left. How many stamps did Jennifer have at first?
original number that Jennifer had ----- x
gave 30 to Keith, so she has x-30 left
gave 2/7 of that to sister, so she has (5/7)(x-30) left, this is 270
(5/7)(x-30) = 270
x - 30 = 270(7/5) = 378
x = 408