Answer:
L= 12 light years
Step-by-step explanation:
for length dilation we use the formula

now calculating Lo
Lo = 12.5×365×24×3600×3×10^8
= 1.183×10^17 m
now putting the values of v and Lo in the above equation we get

= 1.136×10^17 m
L=
m
so L= 12 light years