Answer: she spent $48 on the jacket
Explanation:
Lucy goes to a department store and spends $90 on clothing. This means that all the money she spent at the store is $90
She buys a dress for $30,a hat for $12, and also buys a jacket.
Let $x = the cost of the jacket. Therefore, total amount spent at the store = amount spent on dress + amount spent on hat + amount spent on jacket. It means that
90 = 12 + 30 + x
x = 90 - 12 -30 = $48