R1<- M[1000]
R3<- M[R2+4]
R4<- R1xR2
R5<- R1/R2
R6<- R4-R5
In Operand forwarding, extra hardware is required which can directly forward data from Ex to EX, from M/M to EX and in Write back stage on rasing edge, registers can be updated and on falling edge resigters can be read in the same cycle.
Answer is 15-10=5
Without operating Forwarding:
With operand forwarding:
PS: there is no operand forwarding from EX of 2nd instruction to the EX of 3rd instruction, because 2nd Inst is a read memory operation which will happen in 5th cycle