Tricky but not crazy hard. You could use th x/y method where you turn it into a cross multiplication fiasco.
or you can try your guesses through what ever equals 1/2 when you add one to the denominator. the answer you are looking for is 2/3
2/3 + 1 for the numerator = 1.
2/3 + 1 for the denominator = 1/2.