(5a-2)/(2-3a) = (5*22/15 - 2)/(2-3*22/15) = (110/15 - 2)/(2-66/15) = (110/15-30/15) / (30/15-66/15) = 80/15 / -36/15 = 80/15 * -15/36 = -80/36
и
(5a-2)/(2-3a) = (5*-22/15 - 2)/(2-3*-22/15) = (-110/15 - 2)/(2+66/15) = (-110/15-30/15) / (30/15+66/15) = -140/15 / 96/15 = -140/15 * 15/96 = -140/96