I would say the third option, Density Independent.
I hope this helps!
Answer:
a) A triangle which the angles ratio is 1 : 2 : 3 is a 30º - 60º - 90º right triangle.
b) The shortest side is opposite to the shortest angle. So, we can calculate it using sin 30º.



Train A weighs 181 tons and train B weighs 70 tons.
1) either you'll get a negative number
Or
2) You'll get a positive Number..
But I'm guess you'll get a positive number