Question 955323
(LA TO TOKYO)+NY=8939
NY=(LA TO TOKYO)-2001
SUBSTITUTE: (LA TO TOKYO)-2001) FOR NY IN THE FIRST EQUATION.

(LA TO TOKYO)+(LA TO TOKYO)-2001=8939
2(LA TO TOKYO)-2001=8939
2(LA TO TOKYO)=8939+2001
2(LA TO TOKYO)=10,040
(LA TO TOKYO)=10,040/2
(LA TO TOKYO)=5020 ANS. 
PROOF:
5020+NY=8939
NY=8939-5020
NY=3919 ANS.
3919+5020=8939
8939=8939