Please help i have no idea how to do this

Addison painted her room. she had 5 0 5050 square meters to paint, and she painted at a constant rate. after 2 22 hours of painting, she had 3 5 3535 square meters left. let a t a(t)a, left parenthesis, t, right parenthesis denote the area to paint a aa (measured in square meters) as a function of time t tt (measured in hours). write the function's formula.