Help please the last answer is 5N to the left but it didn’t fit in

Of four points are collinear, they are also coplanar

Given the two similar triangles, how do i find the missing length? if a=4, b=5, and b'=7.5 find a'

Triangles abc and dfg are given. find the lengths of all other sides of these triangles if: b ∠a≅∠d, ab·dg=ac·df, ac=7 cm, bc=15 cm, fg=20 cm, and df-ab=3 cm.