1) x - (560/4) = 1800
х - 140 = 1800
х = 1800 + 140
х = 1940
2) у * (80/20) = 1800
у * 4 = 1800
у = 1800/4
у = 450
24:6=4, 27:6=4(ост.5), 10:5=2, 12:5=2(ост.4), 12:4=3, 15:4=3(ост.7).