5Х + 10Y - 3 = X + 5
4X + 10Y - 8 = 0
/////////////////////////////////
4X - 12Y - 50 + Y = 0
4X - 11Y - 50 = 0 ( * ( -1))
( -4X) + 11Y + 50 = 0
4X + 10Y - 8 = 0
21Y + 42 = 0
21Y = ( -42)
Y = ( - 2)
4X - 20 - 8 = 0
4X = 28
X = 7
ОТВЕТ: X = 7 ; Y = ( - 2)