Question 1141852
for the first, multiply both sides by 1.014185.  Then move the 13.1 over by adding it to both sides.
-1.28=(x-13.1)/1.014185
answer is x=11.80

Second is -1.28=(x-21.5)/0.521775  


do it the same way, by multiplying both sides by 0.521775 then adding 21.5
this gives 20.83
If for some reason the second one is a 90% CI with z=1.645, and one is using the left interval, then the answer would be 20.64 or 20.6