Machine G takes 8 minutes to cut 120 pieces of lumbers. Machine H takes 10 minutes to cut 60 pieces of lumbers. Machine J takes 7 minutes to cut 84 pieces of lumber. 

1. Which is the faster combination, G and H or H and J? (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 G alone:
8 min → 120 pieces
1 min → 120 ÷ 8 = 15 pieces

Time taken by Machine H alone:
10 min → 60 pieces
1 min → 60 ÷ 10 = 6 pieces

Time taken by Machine J alone:
7 min → 60 pieces
1 min → 84 ÷ 7 = 12 pieces

Time taken by Machine G and Machine H together:
1 min → 15 + 6 = 21 pieces

Time taken by Machine H and Machine J together:
1 min → 6 + 12 = 18 pieces

Machine G and H are the faster combination.

(b)
Number of more pieces of lumbers that can be cut by the faster combination (Machine G and H) in 1 minute
= 21 - 18
= 3 

Answer(s): (a) G, H or H, G; (b) 3