I'll help you out with 3 questions.
For #1, you kind of figured it out yourself
That 90 degree angle on paper means that m/1 and m/2 make up 90
If m1 is 50, then just subtract m1 (50) from 90, making it 40. m/2 is 40
If Angle M4 is 45 degrees then angle M3 is 180-45 since they both make up a 180 degree angle.
There are 180 degrees in a triangle
If m 8 = 78
and m 9 = 60
m 10 is 180 - 78 - 60