20.83 would be written as:
20 83/100
This is why.
The 20 is the whole number
The 83 is is the tenths and hundredths place
Since the 3 is in the hundredths place, it makes the 83/100 what it is.
So, the answer would be 20 and 83/100
I am assuming that you can only pick one answer per question.
Let's imagine there are two questions on the test. I would:
1) Consider the first question. How many possible ways could you answer it?
2) Consider the second question. How many ways can you answer that?
If you wrote out all the possibilities, how many combinations of answers would you get across the two questions?
Answer:

Step-by-step explanation:
The surface area of the triangular prism consists of three rectangles and two triangles.
Rectangle One - 5 x 12 = 60 cm^2
Rectangle Two - 4 x 12 = 48 cm^2
Rectangle Three - 3 x 12 = 36 cm^2
Triangles - 2 x 1/2 x 3 x 4 = 12 cm^2
Thus, the total surface area of the solid is 
Yes :-)
3/10 = 30/100 or 30%