Three planks of different lengths, M, N and P are nailed together to make a frame as shown. Plank M has 3 holes which divide it into 4 equal parts. Plank N has 4 holes which divide it into 5 equal parts and Plank P has 5 holes which divide it into 6 equal parts. In the frame, the holes X, Y and Z are three corners of an equilateral triangle. Plank M is 216 cm long. What is the total length of Plank M, Plank N and Plank P?
Length of Plank M = 216 cm

Length of each interval of Plank M
= 216 ÷ 4
= 54 cm

Length of 2 intervals of Plank M
= 2 x 54
= 108 cm

Length of each interval of Plank N 
= 108 ÷ 3
= 36 cm

Length of Plank N
= 5 x 36
= 180 cm

Length of each interval of Plank P
= 108 ÷ 4
= 27 cm

Length of Plank P
= 6 x 27
= 162 cm

Total length of Plank M, Plank N and Plank P
= 216 + 180 + 162
= 558 cm

Answer(s): 558 cm