Question 593819
the object is to eliminate one of the variables by combining the equations


the absolute value (number) of the coefficients of the variable must be equal
___ if the coefficients have the SAME sign, then you subtract to eliminate the variable
___ if the signs are DIFFERENT, adding the equations will eliminate the variable


looking at your example; multiplying the 1st equation by 2 makes the x-coefficients in the two equations the SAME
___ subtracting the equations eliminates the x-terms and gives ___ -7y = -28



another solution; multiplying the 2nd equation by 3 makes the numbers of the y-coefficients equal with DIFFERENT signs
___ adding the equations eliminates the y-terms and gives ___ 14x = 70



sometimes, you may have to multiply both equations by different numbers to get a set of coefficients to "match up"