The normal cost is $69.50. The dress is on sale for 45% off. That menas the new price is 55% of the actual price because:

Multiply 55% by 69.50. First change 55% to a decimal.
To change a percent to a decimal, move the decimal point 2 places to the left and remove the percent sign.

Now multiply by 69.50

The sales price of the dress is $38.23