22.
S₁ + S₂ S/2 + S/2 2S/2
Vср. = -------------- = ---------------------------- = ---------------------------------- =
t₁ + t₂ S/2 : 84 + S/2 : 108 S/2 * 1/84 + S/2 * 1/108
S S S
= ---------------------- = ---------------------------- = ------------------------------ =
S/168 + S/216 9S/1512 + 7S/1512 16S/1512
= S/1 : 16S/1512 = S/1 * 1512/16S = 1/1 * 1512/16 = 1512/16 = 94,5 км/ч