Answer:
20(E)
Step-by-step explanation:
Printing press R, S and T are working together at their respective constant rate.
They can do a job for 4 hours.
Let r, s and t be the time for printing press R, S and T to complete the job alone at their respective constant rate.
Rate of printing press R = 1/r
Rate of printing press S = 1/s
Rate of printing press T = 1/t
Rate = job / time
R + S + T = 4
1/r + 1/s + 1/t = 1/4
S + T = 5
1/s + 1/t = 1/5
Substitute 1/s + 1/t = 1/5 in the equation 1/r + 1/s + 1/t = 1/4
1/r + 1/5 = 1/4
1/r = 1/4 - 1/5
1/r = (5 - 4)/ 20
1/r = 1/20
r = 20 hours
It takes the printing press R 20 hours to complete the job alone
Answer:
i need help please with my maths
Step-by-step explanation:
I think the answer is the second one, let me know if I’m wrong
Answer: False. 21 Shelves.
Step-by-step explanation:
First, 12 x 31= 372
This indicates that there are 372 books.
Then, 372 ÷ 18= 20.6666666667
Since we have a decimal that is above 4 we round up.
This leaves 21 shelves needed for all the books o fit on a shelf.