Suppose that in a certain jurisdiction, license plates have 4 letters followed by 3 digits and all such character sequences are possible. (a) Show that the number of license plates that have exactly...

Suppose that in a certain jurisdiction, license plates have 4 letters followed by 3 digits and all such character sequences are possible.

(a) Show that the number of license plates that have exactly two T’s and end in a 5 is 375,000.

(b) Show that the number of license plates have the letter T and the digit 4 (someplace) in them is 17,981,121.