Size of instruction = 24 bit.
Size of register = 32 bit
No.of instructions = 49
Instruction contain opcode, R1, R2, Immediate operand
Bits for opcode= 6 bit (For representing 49)
Bits for R1 = 5 bit (For representing 32)
Bits for R2 = 5 bit (For representing 32)
Bits left for Immediate operand = 24-(6+5+5) = 8 bit
It is given immediate operand is signed integer( by default 2's complement)
Range of 2's complement in 8 bit = -128 to 127 (Minimum is 128)
Hence -128 is the answer.