m( <A)+m(<B)=90 grade => m(<B)=90-m(<A)
m( <A)-m(<B)=30 grade 40’20”
m(<A)- [90-m(<A)]= 30 grade 40’20”
2m(<A)= 30 grade 40’20”+90 grade
m(<A)=120 grade 40’ 20” :2
m(<A)=60 grade 20’ 10”
m(<B)=90 grade -60 grade 20’ 10”
m(<B)=89 grade 59’60”- 60 grade 20’ 10”
m(<B)=29 grade39’ 50”
R: m(<A)=60 grade 20’ 10”
m(<B)=29 grade39’ 50”