5/6(4,2х - 1 1/5у) - 5,4(2/9х - 1,5у) = (5/6 * 4,2х - 5/6 * 1 1/5у) - 5,4 * 2/9х - (-5,4) * 1,5у = (5/6 * 42/10х - 5/6 * 6/5у) - 54/10 * 2/9х - (-54/10) * 15/10у =
7/2х - у - 6/5х + 81/10у = 7/2х - 6/5х -у + 81/10у = 35/10х - 12/10х - 10/10у + 81/10у = 23/10х + 71/10у = 2,3х + 7,1у