Answer:
[tex]\large\boxed{x=35^o}[/tex]
Step-by-step explanation:
We have the equation:
[tex]56^o+y+51^o=180^o\\\\(56^o+51^o)+y=180^o\\\\107^o+y=180^o\qquad\text{subtract}\ 107^o\ \text{from both sides}\\\\y=73^o\\\\\text{We know: the sum of the measures of the angles of the triangle}\\\text{is equal to}\ 180^o.\\\\\text{Therefore we have the equation:}\\\\x+y+72^o=180^o\qquad\text{put the value of}\ y\\\\x+73^o+72^o=180^o\\\\x+145^o=180^o\qquad\text{subtract}\ 145^o\ \text{from both sides}\\\\x=35^o[/tex]
