First of all, we know that the angle with the red square is 90 degrees; that square is a symbol that represents right angles. If that angle is 90 that must mean that line t and line a are perpendicular. In a perpendicular intersection, 4 right angles are created. Additionally, since line b is parallel to line a; it must also be perpendicular with line t. Therefore, all of those angles are also 90 degrees.
The answer can also be found using the properties of 2 parallel lines and a transversal like corresponding angles and alternate side interior angles.
