1. Convert binary to decimal: 10111101₂ = 128 + 32 + 16 + 8 + 4 + 1 = 189₁₀.
2. Convert octal to decimal: 1101₈ = 1*512 + 1*64 + 0*8 + 1*1 = 577₁₀.
3. Convert hexadecimal to decimal: 111₁₆ = 1*256 + 1*16 + 1*1 = 273₁₀.
4. Sum the decimal values: 189 + 577 + 273 = 1039.