Aaron had $ 2100 left after spending 30 % of the money he took for shopping. how much money did he take along with him?

Now, he has 2100 left, he already spent 30% of what he took along, well, 100% - 30% is just 70%, therefore, what he has left, namely the 2100, is really the 70% of the whole amount, let's say he took along "x", thus "x" is the 100%, then,

Im pretty sure it’s is b 1.6 mi