Question

I REALLY NEED HELP. Maria rented the same car twice in one month. She paid $180 the first time for 3 days and drove a total of 150km. The next time, she also paid $180 and had the vehicle for 2 days and drove 400 km. what was the cost per day? per kilometre?

Answer 1

Cost per day? 

Add together the amounts paid.  Then add together the number of days.
Then divide the total amount by the total # of days:

 $180 + $180            $360
----------------------- = ----------   = $72/day on average.
 3 days + 2 days       5 days
                                                                   $360
Find the cost per kilometer  similarly:   -------------------------  =  ??
                                                               150 km + 400 km

Answer 2

Let x be the cost per kilometer and y be the cost per day:

3y+150x =180
y=(180/3)/(150/3)x
y=60/50x...(1)

2y + 400x =180...(2)

put (1) into (2)
2(60-50x)+400x=180
180-100x+400x=180
300x=360
x=1/5 or can be written as (0.2)

thus the cost perkilometer is $0.2

put the answer x into (2)
2y + 400(0.2) =180
2y=180-80
y=$50

thus the cost per day is $50

hope it helps!