Let x be the price for kilometers and y be the price per days. We'll have:
250x+2y = 66
700x +3y = 138
We'll use the addition method to solve the system:
250x+2y = 66 (*-3)
700x+3y = 138 (*2)
-750x - 6y = -198
1400x +6y = 276
Now adding the equations:
-750x +1400x -6y+6y = 78
650x = 78
x= 78/650
x= 0.12
250x+2y = 66
250*0.12 +2y = 66
2y = 66-30
2y = 36
y = 18
Remember we started by defining the x is the price by km and y is the price by day.
Answer: The price per km is $0.12 and the price per day is $18.