There is a missing graph in the problem given. However, we can simply solve the equation using the given data.
Items to be sold: scarves and hats. Minimum of 20 items sold in all.
Scarves sell for 10 each and hats sell for 20 each. Must sell at least 300 worth of merchandise to make profit.
Let s represent scarves and h represent hats.
10s + 20h > 300
s + h > 20
We use inequality because the problem states "at least".
s + h = 20
10s + 20h = 300
s = 20 - h
10(20-h) + 20h = 300
200 - 10h + 20h = 300
10h = 300 - 200
10h = 100
h = 100/10
h = 10
s = 20 - h
s = 20 - 10
s = 10
s + h > 20
10 + 10 > 20
10s + 20h > 300
10(10) + 20(10) > 300
100 + 200 > 300