I need help pls and thank you

(for these solve of x )

7)x= -9
all angles in a triangle should equal 180. 90+55= 145
180-145= 35, the last angle should equal 35°
to get x you need to subtract 44 from 35
35-44=-9
x=-9
8) x=12
90+40=130
180-130=50
so the last angle is 50°
10+50=60
60/5=12
x=12

A) for the n row: 22+(n-1)×6therefore,b) 100-22=78that means (n-1)×6=7878÷6=1313+1=1414th row has 100 seats