Very confused

Question

Some states have a single area code for the entire state. To such states have area codes where one is double the other. If the sum of these integers is 1407 find the two area codes.

Answer 1

Let x and y be the 2 codes, with y being the larger code.

 

Then the given conditions become:

 

y = 2x

 

x + y = 1407

 

Solve the 2 equations above by substitution:

 

x + 2x = 1407

3x = 1407

x = 1407/3 = 469

 

Then y = 2x = 2*469 = 938

 

The 2 codes are 469 and 938.  You can test the solution.