Answer:
u = [tex]{\boxed{\sf{\: 3 \:}}}[/tex]⁰
Step-by-step explanation:
So, according to the question :
[tex]\begin{gathered} \qquad{\longrightarrow{\sf{Sum \: of \: all \: angles = {180}^{\circ}}}}\\\\ \qquad{\longrightarrow{\sf{{74}^{\circ} + {52}^{\circ} + 18u = {180}^{\circ}}}}\\\\\qquad{\longrightarrow{\sf{{126}^{\circ} + 18u = {180}^{\circ}}}}\\\\\qquad{\longrightarrow{\sf{18u = {180}^{\circ} - {126}^{\circ}}}}\\\\\qquad{\longrightarrow{\sf{18u = {54}^{\circ}}}}\\\\\qquad{\longrightarrow{\sf{u = \dfrac{54}{8}}}}\\\\\qquad{\longrightarrow{\sf{u = {3}^{\circ}}}}\\\\ \qquad\star{\underline{\boxed{\frak{\pink{u = {3}^{\circ}}}}}}\end{gathered}[/tex]
Hence, the value of u is 3⁰.
[tex]\rule{300}{2.5}[/tex]