The length of a wooden block is 9 m 4 cm long. Emma cut the wooden block into 3 pieces. The length of the first piece of the wooden block is 42 cm. The length of the second piece of the wooden block is 2 m shorter than the third piece. What is the length of the third piece of wooden block?
1 m = 100 cm

Difference in the length between the second and the third piece
= 2 m
= 2 x 100
= 200 cm

Length of a wooden block
= 9 m 4 cm
= 9 x 100 + 4
= 904 cm

Length of the first piece = 42 cm
Length of the second piece = 1 u
Length of the third piece = 1 u + 200 cm

1 u + 1 u + 200 + 42 = 904
2 u + 242 = 904
2 u = 904 - 242 = 662
1 u = 662 ÷ 2 = 331 

Length of the third piece of wooden block
= 1 u + 200
= 331 + 200
= 531 cm

Answer(s): 531 cm