From the figure, we understand that ∠1 and ∠3 together form a straight line.
Thus, ∠1+∠3=1800
⇒350+∠3=1800
⇒∠3=1450
Now, since l and m are parallel lines cut by transversals s and t, ∠3 an ∠4 are corresponding angles.
We know that corresponding angles are equal. Thus ∠4=∠3=1450
Similarly ∠2 an ∠4 are corresponding angles.
Thus ∠2=∠4=1450