To find the approximate difference in the percentage of people that liked pepperoni on their pizza and the percentage of people that only liked cheese pizza, we need to find the percentage of people that liked pepperoni and the percentage of people that only liked cheese, and then subtract the smaller percentage from the larger percentage.
From the graph, we can see that 30 people liked pepperoni, 20 people liked mushrooms, 15 people liked sausage, and 10 people liked cheese and olives.
The total number of people Jimmy asked is 30+20+15+10 = 75
The percentage of people that liked pepperoni is 30/75*100 = 40%
The percentage of people that only liked cheese is 10/75*100 = 13.33%
The difference between 40 and 13.33 is 26.67%.
So, the approximate difference in the percentage of people that liked pepperoni on their pizza and the percentage of people that only liked cheese pizza is 26.67%.