If x > 1, Y > 1 and X + y = 20, then the maximum value of lgx + lgY is?

If x > 1, Y > 1 and X + y = 20, then the maximum value of lgx + lgY is?

Lgx + lgY = lgxy, so find the maximum value of XY
20 = x + Y > = 2 times the root XY, so XY