Work=speed times time (my equation to help me figure it out)
ok, 10 men take 84 days to complete a job
therefor, each man completes 1/10 of the job in 84 days
each man does 1/840 of the job per 1 day
so, if we had 5 more, or 15 men
15 times 1/840 times xdays=1 job complete
15/840 times xdays=1job
times both sides by 840/15
xdays=840/15
xdays=56
56 days it would take
        
             
        
        
        
Answer:
51°
Step-by-step explanation:
Given 
<QPR = 39°
<PQR = 90° ( inscribed angle in semi circle) 
Now 
<QPR + <PQR + <PRQ = 180° { being sum of angles of triangle) 
39° + 90° + <PRQ = 180°
 <PRQ = 180° - 39° - 90°
 <PRQ = 51°
Hope it will help :)
 
        
             
        
        
        
to be sure that 2 of them will be blue i have to select 7+2=9 balls
7+8=15 balls in the urn
P=9/15
to be sure that 4 of them will be yellow i have to select 8+4=12 balls
P=12/15
        
             
        
        
        
Answer:
B
Step-by-step explanation: