The term for this is called a supplementary angle if I recall correctly. The lines look straight so that’s probably what is applied.
If you set up that as a straight angle, you’ll get the equation 180*=x*+60*+61* Simplify 180*=x*+121* Subtraction property 180*-121*=x*+121*-121* Simplify X=59
That’s how I’ve interpreted this question, sorry if i got it wrong.
