Answer: $22.50
Step-by-step explanation: In order to fine the sale price, we first need to find the discount.
Original Price x Rate of Discount = Discount
30 x .25 = 7.5 ⇒ Discount
Original Price - Discount = Sale Pice
30 - 7.5 = 22.5
So the sale price of the cake is $22.50.