Jen was making cake pops for the bake sale. After 3 hours, she had completed half of the work. She called Maryna for help and together they finished everything in half an hour. How long would it take Maryna to finish the job alone if she replaced Jen after Jen baked for 3 hours?

Answer 1

"After 3 hours, she had completed half of the work"
... so it would take Jen 6 hours to do the entire job

"together they finished everything in half an hour"
... Jen does an additional [1/2 / 6] or 1/12 of the entire job
... so Maryna does 5/12 of the whole job in 1/2 hr

(5/12) / (1/2) = (6/12) / t ... the time for Maryna to finish on her own
... she would be doing 6/12 (half) of the whole job

t = (1/2 * 6/12) / (5/12) ... hrs

Answer 2

36 minutes