Can the ratio of a parents age to his/her child's age ever be exactly 3:2? Explain.

Yes. If your parent is 90 then it means you are 60. Which then means that they had you when they were 30 which is normal.

Sure:

90 year old parents : 60 year old children (had kids at 30; very reasonable)

60 year old parents : 40 year old children (had kids at 20; unlikly but possible)

45 year old parents : 30 year old children (had kids at 15; very unlikly but not impossible)