Susan has $450. she uses 30% of her money to buy a dress and 20% of the remainder to buy a pair of shoes. How much money does she have left?

$252

Explanation: First off, we want to do 450(0.7). The reason we do this is because the problem says she uses 30% of her money, meaning it goes down by 30%, not that the amount of money becomes 30% of what it originally was. 450(0.7) = 315. Next, we want to do 315(0.8) because it says she uses 20% of the REMAINDER. 315(0.8) = 252, and once you label it, it will become $252.