<span>Standard notation is when a number is completely written out using numerical digits
Hope it helps</span>
Let N be the number of items sold and p the price.
Since the variation is inverse, then the relation between N and p is:

For N=20000 and p = $9.5, we get the formula:

If p = 8.75, then the number of items sold can be computed using the formula:
The answer is 60.7 because 90-29.3=60.7