It takes 21 minutes for 5 people to paint 7 walls. how many minutes does it take 3 people to paint 10 walls

21/7=3mins per wall with 5 people.
Because we assume that all of the people paint at the same rate, 3 X 5=15 mins for one person working alone.
15/3=5 mins per wall with 3 people X 10 people= 50 mins for 3 people to paint 10 walls.

The answer is 50 mins.

answer:

There is no proportional relationship since the slope is not the same.  Tank B is filling up faster than Tank A and you can see that by their plotted points.  Tank B starts at 0 and gets to 200 in 1.5 minutes which is a slope of 200/1.5 = 133.33 per minute.  While Tank B starts at around 620 and get to 800 in 1.5 minutes which is a slope of about 800-620 = 180/1.5 or 120 per hour.  There is a different therefore they are not proportional.