Answer:
23.38 years
Explanation:
Speed of Allison = 0.83 c = v
Time passed according to Allison = Δt = 29.5 years
Time dilation
[tex]\Delta t'=\frac{\Delta t}{\sqrt{1-\frac{v^2}{c^2}}}\\\Rightarrow \Delta t'=\frac{29.5}{\sqrt{1-\frac{0.83^2c^2}{c^2}}}\\\Rightarrow \Delta t'=\frac{29.5}{\sqrt{1-0.83^2}}\\\Rightarrow \Delta t'=52.88\ years[/tex]
For Nora 52.88 years would have passed
So, their age difference would be 52.88-29.5 = 23.38 years