12x+48.3=50.7
12x=50.7-48.3
12x=2.4
x=2.4/12
х=0,2
11.2x+3.7=7.6
11.2x=7.6-3.7
11.2x=3.9
x=3.9/11.2
х=0,34821428571
(5.4y+8.3)*2.1.=23.1
раскроем скобки
11.34y+17.43 = 23.1
11.34y-5.67 = 0
11.34y = 5.67
y = 0.5
12x+48.3=50.7
12x=50.7-48.3
12x=2.4
x=2.4/12
х=0,2
11.2x+3.7=7.6
11.2x=7.6-3.7
11.2x=3.9
x=3.9/11.2
х=0,34821428571
(5.4y+8.3)*2.1.=23.1
раскроем скобки
11.34y+17.43 = 23.1
11.34y-5.67 = 0
11.34y = 5.67
y = 0.5