The answer should be 390=60s, assuming s is the number of shelves he would need.
By the way, if you want the answer using this formula:
390=60s
390/60=s
6.5=s
s=6.5
I think you divide 5/9 divided by 2/3.
5/9 divided by 2/3=4/3 simplified=2/3.
Just know I'm terrible at math so this could be like totally off the hook crazy and wrong.
Easy clap I like monkeys and bananas
Pauline's average speed for this trip is 64 km/hr.
<em><u>Explanation</u></em>
First we will convert each 'minutes' into 'hours' . So......
40 minutes =
and 23 minutes = 
Now, 
So, the distance traveled for first 40 minutes at 88 km/hr speed
,
the distance traveled for next 40 minutes at 75 km/hr speed
and
the distance traveled last 23 minutes at 49 km/hr speed 
So, <u>the total distance traveled </u>
She spends 17 minutes eating lunch and buying gas.
So, <u>the total time taken for the trip</u> 
Thus, Pauline's average speed for this trip = (Total distance / Total time)
<em>(Rounded to the nearest km/hr)</em>