A line and a plane intersect at a

In the diagram, the ratio of ab to ae is (1/2) . what is the ratio of the length of to the length of ?

Can someone me do math because i am having a breakdown rn because i don’t get it

Molly shared a spool of ribbon with 12 people. each person received 3 feet of ribbon. which equation can she use to find r, the number of feet of ribbon that her spool originally had?