Need quick ! which operations on the system of equations could be used to eliminate the x variable? 2x-y=4 x-2y=-1 select the correct answer below. a. divide the first equation by 2 and add the result to the first equation b. divide the first equation by -4 and add the result to the first equation c. multiply the second equation by 4 and add the result to the first equation d. multipy the second equation by -2 and add the result to the first equation