PLSSS HELP IF YOU TURLY KNOW THISS

The transitive property of equality states that: o if a = b, then bra o if a = b, then ac = bc o if a = b and b= c, then a = if a = b and c= c, then a + b = b + c

If sr is 4.5cm and tr is 3cm, what is the measure in degrees of angle s?

What are the exclude value of mn+3m