Find the interest rate on a loan charging $1026 simple interest on a principal of $4750 after 6 years.

Find the principal of a loan at 4.2% if the simple interest after 5 years 6 months is $1386.

Find the term of a loan of $100 at 4.5% if the simple interest is $36.

How much should be invested now at 5.2% simple interest if $9828 is needed in 5 years?