5/8 икс -(1/4икс-1/12игрик)+1/3игрик=

=(5/8-1/4)x+(1/12+1/3)y=3/8x+5/12y

5/8х - ( 1/4х - 1/12y ) + 1/3y = ( 5/8x - 1/4x ) + ( 1/12y + 1/3y ) = ( 5/8x - 2/8x ) + ( 1/12y + 4/12y ) = 3/8x + 5/12y