Car consumption

When driving in the city, the car has an average consumption of k liters of gasoline per 100 km, but when driving on the highway, it consumes an average of 20% liters less. Express the consumption of a car if it travels 25 km in the city and 75 km on the highway. Express the result as a multiple of k.

Correct answer:

x =  0.85 k

Step-by-step explanation:

$$\begin{gathered} r=100\%-20\%=1-\frac{20}{100}=0.8 \\ x=\frac{25\cdot 1+75\cdot r}{25+75}=\frac{25\cdot 1+75\cdot 0.8}{25+75}=0.85\text{k} \end{gathered}$$

Try another example