Three planks of different lengths, S, T and U are nailed together to make a frame as shown. Plank S has 3 holes which divide it into 4 equal parts. Plank T has 4 holes which divide it into 5 equal parts and Plank U has 5 holes which divide it into 6 equal parts. In the frame, the holes W, X and Y are three corners of an equilateral triangle. Plank S is 360 cm long. What is the total length of Plank S, Plank T and Plank U?
Length of Plank S = 360 cm

Length of each interval of Plank S
= 360 ÷ 4
= 90 cm

Length of 2 intervals of Plank S
= 2 x 90
= 180 cm

Length of each interval of Plank T 
= 180 ÷ 3
= 60 cm

Length of Plank T
= 5 x 60
= 300 cm

Length of each interval of Plank U
= 180 ÷ 4
= 45 cm

Length of Plank U
= 6 x 45
= 270 cm

Total length of Plank S, Plank T and Plank U
= 360 + 300 + 270
= 930 cm

Answer(s): 930 cm