Lucy goes to a department store and spends $90 on clothing. She buys a dress for $30, a hat for $12, and also buys a jacket. How much does the jacket cost?

Answer: she spent $48 on the jacket

Step-by-step 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