Answer:
x = -9
m∠A = 45°
Step-by-step explanation:
The interior angles of a triangle always add up to 180°, therefore:
[tex]80+(x+54)+(x+64) = 180[/tex]
Combine like terms.
[tex](x+x)+(80+54+64)=180\\\\2x + 198=180[/tex]
Subtract 198 from both sides, then divide both sides by 2.
[tex]2x=-18\\\\x=-9[/tex]
Solve for m∠A.
[tex]m\angle A= x +54[/tex]
Plug in -9 for x.
[tex]m\angle A= (-9) +54\\\\m\angle A= 45\textdegree[/tex]
