Помогите решить плз

1. х1 = - 10 + 16,(6)*t, x2 = 30 - 10*t, x3 = 15.
2. Встреча: х1 = х2, 4 + 2*t = 8 - 2*t. t = 1 c, xв = 6 м.
3. t1 = 3*S/4*V1, t2 = S/4*V2. Vcp = S/(t1 + t2) = S/(3*S/4*V1 + S/4*V2) =
= 4 *V1*V2/(3*V2 + V1) = 4*60*80/(3*80 + 60) = 64 км/ч.