Emma saves money by splitting her weekly allowance into two parts. She spends \( \frac{3}{5} \) of her allowance on snacks and saves the remaining \( \frac{2}{5} \). If her weekly allowance is $15, how much money does she spend on snacks and how much does she save in a month with four weeks? Let's think step by step and output the final answer within \boxed{}.
user