Irreducible fraction of -30/40

Is by a(-4, 2), b(-2, 4), c(1, 3), d(2, 2).of ofto . of d′ if90° to a′b′c′d′ (-2, 2) of c″ if90° to a″b″c″d″ (4, -2) of a′′′ if° to a′′′b′′′c′′′d′′′ (3, -1) of b″ if° to a″b″c″d″ (4, 2)