Consider 2 triangles: Triangle PMB and Triangle PLA.
Triangle PLA is contained within Triangle PMB.
Side LA is parallel to Side MB.
Point L is located on Side PM. Point A is located on Side PB.
If the ratio PL:LM = 5, then what is PB:PA ??
My answer key says 8/5 but I can't explain why.
My diagram of what you describe is below.
Triangles PMB and PLA are similar so if PL:LM = 5:1 then PA:AB = 5:1. Hence PB:PA = 6:5.
It looks to me as if there is a typo in the problem. I expect that it should say PL:LM = 5:3Harley