Answer
It will take David 18.67 hours or 18 hours, 40 minutes to paint 8 rooms.
Step-by-step explanation
We are asked to calculate the number of hours it'll take David to paint 8 rooms.
Let the number of hours David will take to paint 8 rooms be x
David can paint 3 rooms in 7 hours.
3 rooms = 7 hours
8 rooms = x hours
We can form a mathematical relationship by cross multiplying
3 × x = 8 × 7
3x = 56
Divide both sides 3
(3x/3) = (56/3)
x = 18.67 hours = 18 hours, 40 mins
Hope this Helps!!!