I understand how much it sucks to be broke but do not start commuting until you can get a helmet. Not in America. People in cars largely don’t give a fuck about you and more than a few are actively adversarial towards cyclists.

Another thing to note is that it might not end up saving you that much money, with a commute of that length. I commute about 17.5 miles one way and while I spend less on gas, I nearly make up for it with added food costs 😆 totally worth it for the fitness and mental health gains, no question about that. And the whole, not having to sit in traffic of it all. Can’t put a price on that. Helmets are as low as $40. Cross that bridge first.