How to write 3,801,440 in expanded form

The random variable x is the number of occurrences of an event over an interval of ten minutes. it can be assumed that the probability of an occurrence is the same in any two-time periods of an equal length. it is known that the mean number of occurrences in ten minutes is 5.3. the appropriate probability distribution for the random variable

Negative 5 1/12 + negative 4 1/4 + 6 3/4

Which shows the correct substitution of the values a,b and c from the equation 1=-2x+3x^2+1