Answer:
angle c is 13 as it said in the question
Step-by-step explanation:
 
        
             
        
        
        
Let's first break it down to the time 8 people need for one wall. That would be 10 minutes, right? If one person would have to do it in stead of 8, you'd expect him to take 80 minutes.
To paint 7 walls, he would nee 7x80 = 560 minutes. 10 people would do that 10 times faster, ie., 56 minutes.
I know puzzles like these always have a mindtrick. Did I miss anything?? ;-)
        
             
        
        
        
Two strings are 15 inches and 7 inches long.
You could draw a diagram that has two rulers (that are longer than 12 inches).
Draw a piece of string that is exactly 15 inches on one ruler.
Draw another piece of string on the other ruler at exactly 7 inches.
Then you can find the total length of the two strings by adding 15 and 7 inches.
15 + 7 = 22
The total length of both the strings is 22 inches. You can draw a ruler and a piece of string on it at 22 inches.
        
             
        
        
        
167,000
Step-by-step explanation:
47000 plus 3000 mutipled by 40 gives you your answer