Answer:
x=141
Step-by-step explanation:
(n-2)•180 = Sum of all the interior angles
n = # of sides
(7-2)•180
5•180
900= Sum of all the interior angles
Add all the angles and equal them to 900
125+122+131+x+7+x+107+x-15=900
Add all the numbers up first on the left side
477+3x=900
3x=423
x=141
