Using tables the P value for Z=1.65 is 0.95053 approx.
The P value for Z=0.90 is 0.81594 so the P value for Z=-0.90 is 1-0.81594=0.18406 (because of symmetry).
Therefore to find the probability of Z between these two values we calculate 0.95053-0.18406=0.76647 or 76.65% approx.