rewrite (Rplus_comm (V * T)).
rewrite (Rplus_comm (V * MaxT)).
apply Rplus_le_compat_l.
apply Rmult_le_compat_l.
left; apply (TypeSpeed_pos V).
apply (cond_2 T).
Qed.

(**********)
Lemma MinT_MaxT : (MinT <= MaxT)%R.
unfold MinT in |- *; pattern MaxT at 2 in |- *; rewrite <- (Rplus_0_r MaxT).