Question 184248
to eliminate one of the variables,
in the process of elimination,you can either use addition or subtraction
and for you to eliminate one variable,for example,variables x and y,
then you want to eliminate x,the coefficient of x in the two equations must be the same but must have opposite signs if you'll use addition(to zero out the 2 x's from the 2 equation) or the same signs for subtraction(the sign of the subtrahend is changed to its opposite when performing subtaction)
because you cannot give a value to both variables at the same time,
so you must eliminate one then you'll obtain a value for the other
and then you'll substitute that value to any of the two equations to get the value of the other variable