[tex]V_1=90\frac{km}h\\
s_1=120km\\
\\
s_1=V_1*t_1\\
120km=90\frac{km}h*t_1 /:(90\frac{km}h)\\
120km:90\frac{km}h=t_1\\
120km*\frac{1h}{90km}=t_1\\
\frac43h=t_1\\
\frac43*60min=4*20min=80min=t_1[/tex]
[tex]V_2=90\frac{km}h+20\frac{km}h=110\frac{km}h\\
t_2=30min=\frac12h\\
\\
s_2=V_2*t_2\\
s_2=110\frac{km}h*\frac12h\\
s_2=55km[/tex]
[tex]S=s_1+s_2\\S=120km+55km=175km\\\\T=t_1+t_2\\T=80min+30min=110min=1\frac{5}{6}h=\frac{11}6h\\\\V_{sr}=\frac{S}{T}\\V_{sr}=\frac{175km}{\frac{11}6h}=175km:\frac{11}6h=175km*\frac{6}{11h}=\frac{1050km}{11h}=95,(45)\frac{km}h[/tex]
