Let the number of days be x.
Jameer paints 1 wall in 3 days. In 1 day, he paints 1/3 of a wall. In x days, he paints (1/3)x walls.
June paints 2 walls in 5 days. In 1 day, she paints 2/5 of a wall. In x days, she paints (2/5)x walls.
Working together, in x days they paint (1/3)x + (2/5)x walls.
We want to know the number of days they will take to paint 10 walls, so we let the expression equal 10.
(1/3)x + (2/5)x = 10
(5/15)x + (6/15)x = 10
(11/15)x = 10
x = 10 * 15/11
x = 150/11
It will take 150/11 days which is the same as 13.6363... days or approximately 13.6 days.
