Val rented a bicycle while she was on vacation . she said a flat rental fee of $55.00 , plus $8.50 each day . the total cost was $123 . write an equation you can use to find the number of days , x she rented the bicycle .

Ebuka's monthly rent is $750. if ebuka pays the rent late, his landlord charges 4% interest per week that the payment is late. write a function that gives the total cost r(t), in dollars, of ebuka's rent if he pays it t weeks late.