Article in English: In order to calculate the discount percent of an item, you need to know what the sale price is, and what the original or list price is. For example, you might know that a sweater’s original price is $69, and that it is on sale for $51.75. This will give you the markdown amount, the amount of dollars taken off the original price. For example, since 69−51.75=17.25{\displaystyle 69-51.75=17.25}, $17.25 was taken off the price of the sweater. Use the formula M=PD{\displaystyle M=PD}, where M{\displaystyle M} equals the markdown, in dollars, of the item, P{\displaystyle P} equals the original price of the item, and D{\displaystyle D} equals the discount percent of the item. Be sure to substitute the original price for the variable P{\displaystyle P}, and the markdown for the variable M{\displaystyle M}. For example, if a sweater, originally $69, has a markdown of $17.25, your formula will look like this: 17.25=69D{\displaystyle 17.25=69D}. This will give you the percent of the discount as a decimal. To convert to a percent, move the decimal point two places to the right. For example:17.25=69D{\displaystyle 17.25=69D}17.2569=69D69{\displaystyle {\frac {17.25}{69}}={\frac {69D}{69}}}.25=D{\displaystyle .25=D}So, a $69 sweater on sale for $51.75 is 25% off.

Summary in Indonesian:
Cek semua informasi yang ada. Kurangi harga normal dengan harga jual. Ubah rumus diskon barang. Masukkan harga asli dan pengurangan harganya ke dalam rumus. Bagi tiap sisi persamaan dengan harga awal sweter.