any two opposite angles are equal so,
12x - y = 10x +5y
12x-10x = 5y+y
2x = 6y
so x=3y ----> eqn.1
and, the sum of all angles are equal 360 degrees
so 12x-y + 2x+4y + 10x+ 5 y + 3x + y = 360 then , 27x + 9y = 360 substitute by y= x/3 from eqn.1 the 27x +9(x/3) = 360 27x+3x=36030x=360x=12 substitute in eqn.1 y=x/3 y=12/3y=4 so we get x = 12 & y = 4
