30% off = 30% off =0.7

30% off = multiplied by 0.7

After a 30% discount, the current price is = 100x0.7.

=70 yuan

Cheap 100-70

=30 yuan

The original price of a dress is 100, and the current price is 70 yuan after a 30% discount. The current price is cheaper than the original price, 30 yuan.