11. The sum of these two angles is equal to 180.
So, 3x-4/2+4x+x/2+2=180.
Combine like terms: 4x-4/2+4x+2=180
Find and replace common denominator: 4x-4/2+8x+4/2=180
Combine like terms: 12x/2=180
Simplify: 6x=180, x=30
Check: 90-4/2=43, 120+15+2=137, 43+137=180
