Answer:
C
Step-by-step explanation:
A can be from 2- 9 ( 8 digits)
B can be 0 to 9 (10 digits)
C can be 0 to 9 (10 digits)
Each of the X's can be 0 to 9 (10 digits)
To get the number of possibilities, we multiply them to get:
8 * 10 * 10 * 10 * 10 * 10 * 10 = 8,000,000
But now, 1 number (867-5309) is restricted, so the number of possibilities decrease by 1:
8,000,000 - 1= 7, 999, 999
Correct answer is C
