1)9х-4у=-13 9х-4у-9х+2у=-13+20 -2у = 7 у = -3.5 9х + 14 = -13 9х = -27 9х-2у=-20 х = -3 Ответ:x = -3, y = -3.5 2)8y-x=4 x = 8y-4 16y-8-21y = -20 -5y=-12 у = 2.4 х = 19.2 - 4 = 15.2 2x-21y=-20 Ответ:x=15.2, y = 2.4