Which is the least metric mass?

0.0019 kg
0.19 g
190 cg
1900 mg

How do i do this? i don’t understand

The fence around a quadrilateral-shaped pasture is 3a^2+15a+9 long. three sides of the fence have the following lengths: 5a, 10a-2, a^2-7. what is the length of the fourth side of the fence?

Ahmed plans to add a rectangular sunroom to his house. the sunroom will have a length of 14 feet and a width of 10 feet, and the construction will cost $40 per square foot. how much more would the sunroom cost if it’s width were increased to 12 feet?