m1=51
m2=18
m3=123
m4=39
***remember the 180 rule, and supplementary/complementary angles!
180 rule: all triangle's internal angles add up to 180, this means if you know any two angles you can always find the last one
supplementary angles:
angles that add up to 180, 180 is a straight line so they can be found on almost all triangle problems.
if there is a straight line and you know one of the angles that is on the line, you can find the other one by subtracting it from 180
complementary angles:
same thing ^ but with 90
i hope my explanations make sense! let me know if you have any more questions :)