Răspuns :
a) Mai are de parcurs 100% - 40% = 60% din drum
b) Notăm lungimea drumului cu d.
[tex]\it 40\%\ din\ d=\dfrac{d}{2}-15 \Rightarrow \dfrac{\ \ 40^{(10}}{100}d=\dfrac{d}{2}-15 \Rightarrow \dfrac{4}{10}d=\dfrac{^{5)}d}{2}-\ ^{10)}15 \Rightarrow\\ \\ \\ \Rightarrow 4d=5d-150 \Rightarrow5d-150=4d \Rightarrow 5d-4d=150 \Rightarrow d = 150\ km[/tex]