How do i find the scale factor of wxyz and mnop

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?

Fast! find the length of cu. the triangles are similar. show your work.

On the first of each month sasha runs a 5k race she keeps track of her times to track her progress her time in minutes is recorded in the table