Machine M takes 7 minutes to cut 77 pieces of lumbers. Machine N takes 17 minutes to cut 187 pieces of lumbers. Machine P takes 11 minutes to cut 143 pieces of lumber. 

1. Which is the faster combination, M and N or N and P? (Eg A, B) 
2. In 1 minute, how many more pieces of lumbers can be cut by the faster combination compared to the other combination?

(a)
Time taken by Machine M alone:
7 min → 77 pieces
1 min → 77 ÷ 7 = 11 pieces

Time taken by Machine N alone:
17 min → 187 pieces
1 min → 187 ÷ 17 = 11 pieces

Time taken by Machine P alone:
11 min → 187 pieces
1 min → 143 ÷ 11 = 13 pieces

Time taken by Machine M and Machine N together:
1 min → 11 + 11 = 22 pieces

Time taken by Machine N and Machine P together:
1 min → 11 + 13 = 24 pieces

Machine N and P are the faster combination.

(b)
Number of more pieces of lumbers that can be cut by the faster combination (Machine N and P) in 1 minute
= 24 - 22
= 2 

Answer(s): (a) N, P or P, N; (b) 2