15/6=2.5 which is the scale factor since they are similar triangles. We divide each side of the large triangle by 2.5 to get the sides for the small triangle since they are similar. 20/2.5=8cm
25/2.5=10cm
For the second problem, you put 15/6 and set in equal to x/8 when you cross multiply you get 6x=120 then you divide x=20
For the last problem, you divide 43,75 by 5 then multiply it by 400 to get the kiloliters which equals 3,500.
