Question 368044
Let x = total # of miles travelled. 
Then for the the first 1/5 mile, the cost is $0.50.  For the remaining x-1/5 miles, there are {{{(x-1/5)/(1/10) = 10(x-1/5)}}} one-tenths of a mile.  So the cost for the remaining x - 1/5 miles is {{{0.20*10*(x-1/5) = 2x-0.4}}}dollars.  Thus the total fare is $0.50 + $(2x-0.40) = $(2x + 0.10).