Question

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

Answer 1

a<b means a-b<0
same for c<d. So
(a-b)+(c-d)<0 since bouth (a-b) and (c-d)are <0. From this:
a-b+c-d<0
a+c<b+d

Answer 2

thank you so much..

Answer 3

yw