How many PA license plates have three repeated letters and t

How many PA license plates have three repeated letters and two pairs of repeated numbers (for example: GGG-6996)?

Solution

since we want three repeated letters

only 26 alphabets so 26 cases possible

now for 4 digits and 2 pairs

we want 2 pairs of repeted number

first case, if both pairs can be same then possible no is 10x10 =100(since 10 type of digits from 0-9)

second case, but if both pairs are different then 9x10 = 90

so for both case

first case total possibles = 26 x100 = 2600

for second case = 26 x90 = 2340

since u havent mentioned it i did for both the cases