71999+х-(3078+609*25)=75507
71999+х-3078-15225=75507
53696+х=75507
х=75507-53696
х=21811
Проверим: 71999+21811-(3078+609*25)=75507
93810-18303=75507
75507=75507
<span>(y - 0.18)*0,2=3
0.2y-0.036=3
0.2y=3+0.036
0.2y=3.036
y=3.036/0.2
y=75.9</span>
Х=9*5
Х=9*5=45
Х=45
------------------------
45:5=9
<span> 8 * у - у = y (8-1) = 7y n * 4 + n = 5n</span>