What you have are these numbers: 19, 19, 20, 20, 21, 21, ... 45, 48 [Wrtie down all of these.]
To find the mean, x, add all these numbers and divide by 27.
To find the median, y, find the number that is the middle number.
Fo find the mode, z, find which number is written the most often.
Place these numbers in the formula: x(y - z).
Taken from: geno3141
My answer was -58, that might help.