z−4t=5 I*-3
3z−7t=38
-3z+12t=-15
3z-7t=38
сложим
5t=23
t=4.6
z=5+4t=23.4
(4.6;23.4)
а) 16х100:20=80 8х100:20=40 4х100:20=20
б) 9х100:45=20 180х100:45=400
в) 44Х100:110=40 5,5х100:110=5
г) 120х100:1,5=8000 2,25х100:1,5=150