{3x+7y=-1, 2x-3y=7.

1) there are a lot of necessary information on the Internet 2) the main risk in the Internet-lose the information. This means that someone can know too much about you 3)- 4)because someone may use your information 5)Sometimes a message comes in where it says that you have to send an SMS to this number

домножаем верх на -2, низ на 3 получаем -6x-14y=2 6x-9y=21 складываем -23y=23 y=-1 подставляем во 2 2x+3=7 2x=4 x=2 ответ (2;-1)