Answer:
14.11 km/L
Step-by-step explanation:
If the current price is 'P', the price after 10 years at an increase rate of 3.5% per year will be:
[tex]P_F=P*(1+0.035)^{10}\\P_F=1.411P[/tex]
The rate in km/L required to maintain the same nominal gas consumption is:
[tex]C=\frac{10\ }{P}* \frac{1.411P}{L}\\ C=14.11\ km/L[/tex]
Fuel consumption in 10 years will have to be 14.11 km/L in order for monthly gas consumption to remain unchanged.