Final answer:
The price of the new iPhone was decreased by 20%.
Step-by-step explanation:
To find the percent decrease, you need to calculate the difference between the original price and the sale price, and then divide that difference by the original price.
Step 1: Calculate the difference between the original price ($900) and the sale price ($720):
$900 - $720 = $180
Step 2: Divide the difference by the original price:
$180 / $900 = 0.2
Step 3: Multiply the result by 100 to get the percentage:
0.2 x 100 = 20%
So, the price of the new iPhone was decreased by 20%.