Пошаговое объяснение:
1. 23 475-(x-555)=450
x - 555 = 23475 - 450
x - 555 = 23025
x = 23025 + 555
x = 23580
2. (258+y)-456=78
258+y = 78+456
258+y = 534
y = 534 - 258
y = 276
3. 5а+ 357=951
5a = 951 - 357
5a = 594
a = 594 : 5
a = 118,8
