7z+2x=109 5z + 3x = 81

7z+2x=109 5z + 3x = 81

7z+2x=109

7z+2x-2x=109-2x

7z=109-2x

7z/7=109-2x/7

z = 109/7-(2 x)/7

5z + 3x = 81 solve for x

5(109/7-2x/7)+3x=81

5(109/7-2x/7)+3x=81

5(109/7-2x/7)+21x/7=81

5(109-2x)+21x/7=81

545-10x+21x/7=81

545+11x/7=81

(545+11x/7_*7=81*7

545+11x=567

545-545+11x=567-545

11x=22

11x/11=22/11

x=2

solve for z

7z+2x=109

7z+2(2)=109

7z+4=109

7z+4-4=109-4

7z=105

7z/7=205/7

z=15