PLZ HELP

Jonathan's age is one-third Belinda's age now. In 12 years, Belinda will be m years old.

a) Write an algebraic expression to represent Belinda's age now.

b) Write an algebraic expression to represent Jonathan's age 5 years from now.

c) If m = 36, what will Jonathan's age be 5 years from now?

d) Explain how you found the answers.