Question 384048
There aren't any. This is because:

a + b + c = (1/2)(100a + 10b + c)

2a + 2b + 2c = 100a + 10b + c

98a + 8b - c = 0.

98a + 8b = c

Since a must be at least 1 (since it's a three-digit number) then c is at least 98, which wouldn't work.