Answer:
Step-by-step explanation:
50 degree
a + b + c= 90
30+30+30=90
90=90.
30 is the ans
I used SI system for units
1)meter
2)kilogram
3)kilogram
4)meter
5)Litre
7 and 13
x+y=20
x-y=6
2x=26, x=13, 13+7=20, 13-7=6.
11x5 is 55