here all sum of angles of a triangle should be 180
so
1) 28+42+110=180 right
2)77+98+15=190 wrong so we can change first angle by reducing it 10 which is 67
so 67+98+15=180
3) 31+59+60=150 worng so we can add 30 more o angle 31 to make 180
61+59+60=180