Machine E takes 5 minutes to cut 85 pieces of lumbers. Machine F takes 13 minutes to cut 117 pieces of lumbers. Machine G takes 7 minutes to cut 77 pieces of lumber. 

1. Which is the faster combination, E and F or F and G? (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 E alone:
5 min → 85 pieces
1 min → 85 ÷ 5 = 17 pieces

Time taken by Machine F alone:
13 min → 117 pieces
1 min → 117 ÷ 13 = 9 pieces

Time taken by Machine G alone:
7 min → 117 pieces
1 min → 77 ÷ 7 = 11 pieces

Time taken by Machine E and Machine F together:
1 min → 17 + 9 = 26 pieces

Time taken by Machine F and Machine G together:
1 min → 9 + 11 = 20 pieces

Machine E and F are the faster combination.

(b)
Number of more pieces of lumbers that can be cut by the faster combination (Machine E and F) in 1 minute
= 26 - 20
= 6 

Answer(s): (a) E, F or F, E; (b) 6