Ax^2+bx+c=0 is the standard form, so we add 5 to both sides to get
1*x^2+(-10)x+21=0
There is a 1/2 chance that he will get at least one of the two features.
There are 3 x 4 = 12 possibilities. There are all 4 colors of each 3 sizes.
All 4 of the medium trucks have one of the features.
For the other 2 sizes, only the red truck will have one of the features.
There are 4 + 2 = 6 possibilities out of 12 for a chance of 6/12 or 1/2.
The office manager purchased a total of 12 reams of white paper. :)
