Kate paid $27 for a dress that was on sale at 10% off. What was the original price for this dress?

The original price for this dress was $30

Step-by-step explanation:

If 90% of 30 is 27, we have to find out 10% of 30.

How to find it:

1) You make the 10% of 30 into a proportion

10/100=x/30

(Cross multiply)

100x=300

x=3

2) So now since we've found 10% of 30, we add it on to 27.

27+3=30

Therefore, the original price of the dress that Kate bought was $30.