Question

The cost of petrol rises by 2 cents a liter. last week a man bought 20 liters at the old price. This week he bought 10 liters at the new price. Altogether, the petrol costs $9.20. What was the old price for 1 liter?

Answer 1

Answer:

0.3

Step-by-step explanation:

20x+10(x+2/100)=9.2

30x+0.2=9.2

30x=9

x=9/30=0.3

Answer 2

let the cost of one litre be   X$

the new cost of one litre will be X$+ 2cents              (2 censt =0.02$)

                                              =. (X+.02)$

cost incurred in last week  =  (cost per one liter last week)*(no of litres)

                                            = (X)*(20)  

                                            =  20X

cost incurred in this week  =  (c0st per one litre this week)*(no of litres)

                                            = (X+0.02)*(10)

                                             = 10X+0.2

NOW TOTAL cost incurred  is 10X+0.2+20X =30X+0.2  =9.20

                                              this implies  30X =9

                                                                       X=0.3

so the old price of petrol for 1 liter  is  0.3 $  or  30 cents