The sum of the measures of the angles of a triangle is 180 degrees.
Angles STU and STR are supplementary angles.
Angles R and STR are congruent.
m<STU + m<STR = 180
8x + m<STR = 180
m<STR = 180 - 8x
m<R = m<STR = 180 - 8x
m<RST + m<R + m<STR = 180
7x - 54 + 180 - 8x + 180 - 8x = 180
-9x + 360 = 180
-9x = -126
x = 14
Answer:
thx
Step-by-step explanation: