You paint 13 1 3 of a wall in 14 1 4 hour. at that rate, how long will it take you to paint one wall?

Find the rate at which you work, that is, the # of walls painted per hour:

13 1/3 walls          40/3

 = wall per hour

14 1/4 hr              57/4

Keep 40/3 as it is; invert the divisor (57/4) and then multiply the result by 40/3:

40        4        160 wall

*  = = approx. 0.94 wall in one hour, or 160/171 wall / hr

  3       57        171 hr

walter needs to make at least 5 more cookies but no more than 40. 5 ≤ x ≤ 40

step-by-step explanation:

20 ≤ x + 15 ≤ 55

subtract 15 from all parts

20-15 ≤ x + 15-15 ≤ 55-15

5 ≤ x ≤ 40

this means how many more cookies he has to make

walter needs to make at least 5 more cookies, but no more than 40 cookies; 5 ≤ x ≤ 40