The expression can be simplified as follows:

Let's first simplify the numerator:
tg(155°) = tg(180° - 25°) = -tg(25°)
tg(5°) = tg(180° - 175°) = -tg(175°)

So, the numerator becomes:
(1 + (-tg(25°)(-tg(175°))) = 1 + tg(25°)tg(175°)

Now, let's simplify the denominator:
tg(155°) - tg(5°) = tg(180° - 25°) - tg(180° - 175°) = -tg(25°) + tg(175°)

Therefore, the expression simplifies to:
(1 + tg(25°)*tg(175°)) / (-tg(25°) + tg(175°))