Please help me with this Algebra word problem

Rick and Amy have cleaning jobs. Rick earns $10/hr and takes 8 hours to do a job. Amy ears $8/hr and takes 10 hours to do the same job.

a.How long will it take them to do the job together?

b.How much will Rick earn if he is doing the job himself? How much will Amy earn if she is doing the job on her own? How much will they earn in the spirit of cooperation?

Please help I cant seem to figure this out! Thanks in Advance!

Rick can do 1/8 job in 1 hour.
Amy can do 1/10 job in 1 hour.
Together they can do (1/8 + 1/10 = 9/40) job in 1 hour.
Therefore it will take them 40/9 hr to complete 1 job.

Rick will earn $ 10 (40/9) = $ 44.44
Amy will earn $ 8 (40/9) = $ 35.56
Together they will earn = $ 80.00

If Rick does the job himself, he will earn $ 10 (8) = $ 80.00
If Amy does the job herself, she will earn $ 8 (10) = $ 80.00

for a. im just kinda guessin, 40. for b. rick: $80 amy:$80, for both if they both got paid the same amout of $80, then it would be $160