Answer:
x = 12
Step-by-step explanation:
The sum of the two smaller angles is 140
80+5x = 140
Subtract 80 from each side
80+5x-80 =140-80
5x = 60
Divide each side by 5
5x/5 = 60/5
-12+4y=x..............1
6(-12+4y)+4y=8
-72+24y+4y=8
28y=80
y=3.33
-12+4(3.33)=x
1.32=x