Question

Prove that if a, b, c and d are real numbers, and if a 13 years ago

Answer 1

(a+c) - (b+d) = (a-b) + (c - d).
(a-b) <0 since a <b
(c-d) < 0 since c<b
=> (a-b) + (c - d) < 0
=> (a+c) - (b+d) < 0
=>(a+c) < (b+d)