Question 744651
The problem states:

The combined land area of the countries A and B is 173,973 square kilometers. Country A is larger by 773 square kilometers. Determine the land area of each country. 
Land area A
Land area B 

let x = land area of country B, then we have

x+773+x = 173973
2x = 173200
x = 86600  which is land area of country B
land area of country A = 86600 + 773 = 87373