The statement is too broad. You can only multiply the numerator and denominator to keep it the same if I remember correctly.

1/2 + 1/4 = x
(1×2)/(2x2)  + 1/4 = x
2/4 + 1/4 = x
3/4 = x

(1/2) = (1/2)

(1/2) = (1 + 1 / 2 + 1)

(1/2) = (2/3)

QED

• Terrance Howard