1. 28000+36000:9·3-28000+12=28012
2. 8000·7:1=56000
3. 9000-9000:9=9000-1000=8000
4. 7000·7-901=49000-901=48099
5. 20000+175=20175
552.
a) x + 2x + 2x - 7 = 5x - 7
б) y + 4y + 4y - 10 = 9y - 10
553.
a) 5x - 7 = 68
5x = 75
x = 15
AB = 15, BC = 30, AC = 23
б) 9y - 10 = 197
9y = 207
y = 23
AB = 23, BC = 92, AC = 82