The angle sum property of a triangle:
The total measure of the three angles of a triangle is 180°
[tex]\rm\large\rightarrow \: \: x \: + \: 55 \degree \: + \: 90 \degree \: = \: 180 \degree[/tex]
[tex]\rm\large\rightarrow \: \: x \: + \: 145 \degree \: = \: 180 \degree[/tex]
[tex]\rm\large\rightarrow \: \: x \: = \: 180 \degree \: - \: \: 145 \degree [/tex]
[tex]\rm\large\rightarrow \: \: x \: = \: 35 \degree[/tex]
