Deisha can build a fence in 15 hours, and Travis can build a fence in 12 hours. How long will it take them together to build a fence?

6

Step-by-step explanation:

Deisha's build rate = 1 fence per 15 hours = 1/15 fences per hour

Travis's build rate = 1 fence per 12 hours = 1/12 fences per hour

Working together, their combined rate is 1/15 + 1/12 = 3/20 fences per hour

So it takes them 20/3 = 6 2/3 hours per fence

geometry: triangles

solvers

lessons

answers archive

call the larger triangle abc

then the smaller triangle cde is similar to abc (all angles are equal, aaa).  

ab is the side that is 36, and we wish to find de, the side corresponding to ab

area_cde = area_abc - area_cde --> area_abc / area_cde = 2

let x=length of de

ratio of areas = (ratio of sides)^2

+2+=+%2836%2fx%29%5e2+

+2+=+1296%2fx%5e2+

++x%5e2+=+1296%2f2+=+648+

25.45584

hope this is what you were asking for!

step-by-step explanation: