The Shaw Family is building a patio. One person can place the flagstone at a rate of 4.5 per hour. The equation s = 11h represents the number of stones s that two people can place in h hours. How many more flagstones can 2 people place in 3 hours than one person?

Given that the equation s = 11h represents the number of stones that two people can place in h hours, then in 3 hours, two people can place 11 (3) = 33 stones.

Given that one person can place stones at a rate of 4.5 per hour, then in three hours, one person can place 4.5 (3) = 13.5 stones.

Therefore, in 3 hours, 2 people can place 33 - 13.5 = 19.5 more stones than one person.