(72x+90)/18; 2) (81y+54)/27; 3)(15*85x)/17; 4)(133y*23)/19.
(72x+90)/18 (81y+54)/27 (15*85x)/17 (133y*23)/19
1)72x/18=4x 1)81y/27=3y 1) 15*85=1275x 1)133y*23=3059y
2)90/18=5 2) 54/27=2 2) 1275/17=75x 2)3059y/19=161y
3)4x+5=0 3) 3y+2=0 75x=0 3) 161y=0
4x=-5 3y=-2 x=0 y=0
x=-5/4 y= -2/3