Combined land area

Question

The combined land area of countries A&B is 128,973. Country A's area is 873 square kilometer larger. What is the land area of each country?

Answer 1

(sorry, wrote the number down wrong originally)

 

EQ #1)   A + B = 128,973

 

EQ #2)   A = B + 873       (A'S AREA IS 873 MORE THAN B)

 

 

SUBSTITUTE 2ND EQN A IN 1ST EQN.

 

(B + 873) + B = 128,973

2B + 873 = 128,973

 

2B = 128,100

B   = 128,100/2 = 64,050

 

NOW JUST SUSTITUTE THIS VALUE FOR B IN EITHER OF OUR ORIG EQNS

I'LL USE THE 2ND,  

A = B + 873   SO A = 64,050 + 873 = 64,923

 

SO, WE HAVE A = 64,923  AND B = 64,050  

 

NOW, CHECK THE SUM:  64,923 + 64,050 = 128,973   (checks)