Need help asap please !!

Idon’t understand this.. will someone ? will mark brainliest along with 20 points.

Justin has 750 more than eva and eva has 12 less than justin together they have a total of 63 how much money did

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.