X = 1

x = 2

x = 3

x = 4

x=-12.8 or −64 /5

Step-by-step explanation:

ok easy as pie

interior plus exterior is 180 degrees

so 180-130=50

we know the last angle = 50

now lets add them all up and they should be equal to 180

all traingles interior angles add up to 180

180=(-21x+1)+(11x+1)+(50)

now solve

180=-21x+1+11x+1+50

180=-10x+52

52-10x=180

subtract 52

-10x=128

-12.8=x

x=-12.8 or −64 /5