(x+5)(y-2)=(x+2)(y-1)
(x-4)(y+7)=(x-3)(y+4)
1.
xy-2x+5y-10=xy-x+2y-2
xy-xy-2x-2y+5y+x=-2+10
-x+3y=8
2.
xy+7x-4y-28=xy+4x-3y-12
xy-xy+7x-4y-4x+3y=-12+28
-y+3x=16
-x+3y=8
-y+3x=16
-x=8-3y I*-1
-y+3x=16
x=-8+3y
-y+3x=16
x=-8+3y
-y+3(-8+3y)=16
x=-8+3y
-y-24+9y=16
x=-8+3y
8y=16+24
x=-8+3y
8y=40 ÷8
x=-8+3y
y=5
x=-8+3*5
y=5
x=-8+15
y=5
x=7
y=5
* znak mnożenia
{xy-4y+7x-28=xy-3y+4x-12 /-xy+3y-4x+28
{3y-x=8
{-y+3x=16 /*3
{3y-x=8
+{-3y+9x=48
{8x=56 /:8
{3y-x=8
{x=7
{3y-7=8 /+7
{x=7
{3y=15 /:3
{x=7
{y=5