Simplify:

Need help ASAP ty

The product of 3 and a number increased by 8 is 31

Problem 3 a bank charges a service fee of $7.50 per month for a checking account. a bank account has $85.00. if no money is deposited or withdrawn except the service charge, how many months until the account balance is negative

In chemistry,n molecules of an ideal gas have pressure, volume, and tempersture that stand inthe following relation, where r is constant. solve the equation for n,the number of molecules. pv=nrt