( x / 4 ) + ( у / 6 ) = 1
2x + 3y = - 12
------------------------
( - 18x / 4 ) - ( 18y / 6 ) = - 18
- 4,5x - 3y = - 18
- 4,5x + 2x - 3y + 3y = - 12 - 18
- 2,5x = - 30
x = 12
2 * 12 + 3y = - 12
3y = - 12 - 24
y = - 36 : 3
y = - 12
ОТВЕТ ( 12 ; - 12 )
-------------------------------
40x + 3y = 10
20x - 7y = 5
------------------
- 40x + 14y = - 10
40x - 40x + 3y + 14y = 10 - 10
17y = 0
y = 0
40x = 10
x = 0,25
ОТВЕТ ( 0,25 ; 0 )