Answer: it'll be 4 weeks until you have enough money to buy the iguana.
Step-by-step explanation: You already started off with 12, and the price of the iguana is $48.
Let's picture it like this. Imagine you draw 4 circles. In each circle you put $9 inside. This leaves us off to 4x9, which is 36.
But the full price of the iguana is $48. So when you add 36 with 12, you get $48.