1.
a)
[tex]3.5 \times 60 = 210min[/tex]
b)
[tex]72 \frac{km}{h} = 72 \times \frac{1000}{3600} = \frac{72000}{3600} = 20 \frac{m}{s} [/tex]
c)
[tex]35 \frac{m}{s} = 35 \times 3.6 = 126 \frac{km}{h} [/tex]
2.
[tex]s = 280km \\ \\ t = 4h \\ \\ v = \frac{s}{t} \\ \\ v = \frac{280km}{4h} = 70 \frac{km}{h} [/tex]
