Hello,
I can see this is a clear academic assignment. I can do the problems for 40 but the essay is another 20 so makes it 60 for me. 6$ is freelancer's charge. I can also see this project has been posted by someone who regularly takes work or regularly posts work in freelancer. I would say, we could have 10 % savings if we could collaborate more often, I can reduce cost for a regular work, you could get a better margin. win-win.
Please let me know.
Regards
Aeromaster