There are 75 olives, 40% of which are green. I eat some of the green olives until 10% of the olives that remain are green. How many green olives did I eat?
30 olives are green ... .4 * 75 = 30
(30 - x) / (75 - x) = .1
solve for x
(30 - x) / (75 - x) = .1
solve for x