In order to find this, you need to divide the current cost by the percentage you are paying for. Since it's 75% off, you are paying for 25% of the dress's original cost. Therefore, divide 30 by 25%.
the domain refers to the set of possible input values, the domain of a graph consists of all the input values shown on the x-axis. The range is the set of possible output values, which are shown on the y-axis.