In the given figure three angles are marked x°, 56° and 146 °
When two lines intersect they form two pairs of opposite angles. Vertical angles are always congruent, which means that they are equal.
In the figure angles x ,56 and 146 are formed on two opposite sides of the straight lines are so are vertically opposite angles and hence they are equal.
We can write this as x+56=146.
The first option is the right answer.