SOLUTION: The sum of two numbers is 20. Their difference is 4. Write the system of linear equations first,then solve the system of equations

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Question 523990: The sum of two numbers is 20. Their difference is 4. Write the system of linear equations first,then solve the system of equations
Answer by lagbens(14) About Me  (Show Source):
You can put this solution on YOUR website!
let's call the two unknown numbers "X" and "Y".
so we can write (1)X+Y=20 and (2)X-Y=4.
we have positive and negative Y so Y can be easily eliminated, then we have:2X=24.
divide both side by 2, X=12.
now to get the value of Y we should bring the value of X into one of the equations.
in (1) it would be 12+Y=20(subtract 12 from both side)
Y=8 [final answer must look like (X,Y)or(12,8)]