Solution:Let the third number be Z
Second number = Y
And the first number = X
Z = [1 - (20/100)] × X
Z = 0.8 X
10 Z = 8X
5 Z = 4X ……(1)
Z = [1 + (30/100)] × Y
Z = 1.3 Y
10 Z = 13 Y ……(2)
X + Y + Z = 471
(5Z/4) + (10Z/13) + Z = 471
(65Z + 40Z + 52Z) = 471×52
157 Z = 471 × 52
Z = 3×52 = 156