Assume rf = 0

1. You want to construct a delta-neutral CALL front ratio spread. Long 1x ATM 50 delta CALL, and short 2x 25 delta OTM Call. What strike call will give you a 25 delta? What is the gamma value of the spread?
2. You want to construct a PUT back ratio spread. Long 2 x 25 delta OTM PUT, and short 1x 50 delta ATM PUT. What strikes are the PUT options you are using? What is the gamma value of the spread?