{ 1/x + 1/y = 5/6
{ 2y - x = 1
=>
{ 6y + 6x = 5xy
{ x = 2y - 1
=>
6y + 6*(2y - 1) = 5y * (2y - 1)
6y + 12y - 6 = 10y^2 - 5y
10y^2 - 23y + 6 = 0
y1 = 2 -----------> x1 = 2*y1 - 1 = 2*2 - 1 = 3
y2 = 3/10 -------> x2 = 2*y2 - 1 = 2*3/10 - 1 = -4/10 = -2/5