The length of a wooden block is 7 m 3 cm long. Kylie cut the wooden block into 3 pieces. The length of the first piece of the wooden block is 39 cm. The length of the second piece of the wooden block is 4 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
= 4 m
= 4 x 100
= 400 cm

Length of a wooden block
= 7 m 3 cm
= 7 x 100 + 3
= 703 cm

Length of the first piece = 39 cm
Length of the second piece = 1 u
Length of the third piece = 1 u + 400 cm

1 u + 1 u + 400 + 39 = 703
2 u + 439 = 703
2 u = 703 - 439 = 264
1 u = 264 ÷ 2 = 132 

Length of the third piece of wooden block
= 1 u + 400
= 132 + 400
= 532 cm

Answer(s): 532 cm