Program z9; Var s1,s2,v1,v2,s:integer; t1,t2,v,t:real;Begin write('S1 = '); readln(s1); write('S2 = '); readln(s2); write('V1 = '); readln(v1); write('V2 = '); readln(v2); s:=s1+s2; t1:=s1/v1; t2:=s2/v2; t:=t1+t2; v:=s/t; writeln('Средняя скорость равна = ', v);End.