Machine S takes 7 minutes to cut 133 pieces of lumbers. Machine T takes 16 minutes to cut 128 pieces of lumbers. Machine U takes 11 minutes to cut 165 pieces of lumber. 

1. Which is the faster combination, S and T or T and U? (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 S alone:
7 min → 133 pieces
1 min → 133 ÷ 7 = 19 pieces

Time taken by Machine T alone:
16 min → 128 pieces
1 min → 128 ÷ 16 = 8 pieces

Time taken by Machine U alone:
11 min → 128 pieces
1 min → 165 ÷ 11 = 15 pieces

Time taken by Machine S and Machine T together:
1 min → 19 + 8 = 27 pieces

Time taken by Machine T and Machine U together:
1 min → 8 + 15 = 23 pieces

Machine S and T are the faster combination.

(b)
Number of more pieces of lumbers that can be cut by the faster combination (Machine S and T) in 1 minute
= 27 - 23
= 4 

Answer(s): (a) S, T or T, S; (b) 4