Verified answer

Ответ:

Объяснение:

S1 = S/4

S2= 3*S / 4

S= S1+S2

V1 = 40 км/ч

V2= 60км/ч

Vc = ?

t1=S1/V1 = S/(4*V1)

t2=S2/V2 = 3*S/(4*V2)

Vc = S/(t1+t2) = S / (S/(4*V1) + (3*S/(4*V2))) = 1/ (1/(4*V1) + (3/(4*V2) =

1/(1/(4*40) + 3/(4*60)) = 1/(1/(160) + 3/(240)) = =53.3 км/ч