Answer:
d) 
because that would be the same as 
1. Use the Pythagoras theorem
13^2 = x^2 + 5^2
solve for x and youll get the height of the roof.
2. let x = length of the rpoe)-
x^2 = 9^2 + 12^2
3. Pythagoras again
20^2 = x^2 + 12^2
Answer:
The elevator stops on the 19th floor.
Step-by-step explanation:
On the 16th floor, goes up 12 floors:
16 + 12 = 28
On the 28th floor, goes down 7 floors:
28 - 7 = 21
On the 21st floor, does up 3 floors:
21 + 3 = 24
On the 24th floor, goes down 5 floors:
24 - 5 = 19
Total sets of 4-digits = 6
Total 4-digit numbers formed by one set of number = 4
So, total numbers that can be formed = 6 × 4 = 24
