I took an example.
Prob = 0.001 = 0.1% which means 1 out of 1000 frames result in error.
I wish to send 1000 frames. So, total time to transmit it will be 1000*$T_t$ which is my useful time.
To send 1000 frames without any error, I actually need to transmit 1001 frames.
Thus, total time required will be 1001*$T_t$ + 1001*2*$T_p$
Thus, link utilization = $\frac{useful\:time}{total\:time}$=$\frac{1000*T_t}{1001*T_t + 1001*2*T_p}$
Put $T_t$ = 8ms and $T_p$ = 400ms
Link utilization = 0.009891 = 0.9891%