1. We will have that the original price represents the 100% and we will have that the 30% will represent the dicount value, therefore:
[tex]D_p=O_{v-}\frac{O_v\cdot30}{100}[/tex]Here Dp is the price with discount and Ov is the original value.
2. We will replace the values in the previous function:
[tex]D_p=500-\frac{500\cdot30}{100}\Rightarrow D_p=350[/tex]From this we have, that if the original value was $500 and it got a 30% discount, the final price would be $350.