Joe : h1
Jacob : h2 = h1 + 20 cm
William : h3 = h2 + 20 = h1 + 40 cm
Averell : h4 = h1 + 60 cm
on sait que : h1 + h2 + h3 + h4 = 6.20 m
h1 = 6.20 - (h2 + h3 + h4)
h2 + h3 + h4 = 3 x h1 + 1.20
h1 = 6.20 - 3h1 - 1.20
4 x h1 = 5 ⇒ h1 = 5/4 = 1.25 m
h2 = 1.25 + 0.20 = 1.45 m
h3 = 1.25 + 0.40 = 1.65 m
h4 = 1.25 + 0.60 = 1.85 m