Question

73. If R, S, and T are integers and R + S and

Answer 1

R+S is odd==>R+S=2n+1 (1)
T-S is odd ==>T-S=2k+1 (2)
(1)+(2)==>R+T+S-S=2n+1+2k+1
==>R+T=2(n+k+1) is even

Answer  A