(i) a + b < c + d (ii) b + c < d + e (iii) c + d < e + a (iv) d + e < a + b from (i) & (iii) a + b < e + a ⇒ b < e from (ii) & (iv) b + c < a + b ⇒ c < a (i) – (ii) a – c < c – e ⇒ c > e (i) – (iv) (a – e) + (b – d) < (c – a) + (d – b) from thus d > b (i) + (iii) – (ii) c > d overall a is greatest, b is least