In the given figure, l || m || n and p || q || r. Find the angles x, y, z and t.

Consider, l || n:

x° and 100° are co-interior angles.

Co-interior angles are supplementary:

∴ x° + 100° = 180°

⇒ x° = 180° - 100°

⇒ x° = 80°

y° = x° $\quad$[Corresponding angles]

∴ y° = 80°

Consider p || r and n is a transversal:

z° = x° $\quad$[Alternate angles]

∴ z° = 80°

Now, consider l || m and r is a transversal:

t° = 100° $\quad$[Alternate angles]

x° = 80°, y° = 80°, z° = 80° and t° = 100°