вычислити пож с 1 по 10

проверь 7 номер правильно ли записано?

Х + 36 = 72 + 15                             7)  36 = 78х - 2х
х = 72 + 15 - 36                                   36 = 76х
х = 51                                                   х = 36 : 76
                                                                х = 9/19
135 - х = 102 -15
135 - х = 87                                    8)  45 +30 = 112 - х
х = 135 - 87                                         75 = 112 - х
х = 48                                                   х = 112 - 75
                                                            х =37
2х + 18х + 20х = 151 -31
40х = 120                                      9)  8у  + 3у  = 77
х = 30                                                  11у = 77
                                                             у = 7
41 - 10 - х - х = 81
31 - 2х = 81                                  10) 2а +3а +10а - 4а = 11а
2х = 31 - 81                                          а = 10
2х = -50                                              11а = 11 * 10 = 110
х = - 25

9х - 4х = 135 - 30
5х = 105
х = 21

1. х+36=72+15
х+36=87
х=87-36
х=51

2. 135-х=102-15
135-х=87
х=135-87
х=48

3. 2х+18х+20х=151-31
40х=120
х=120:40
х=30

5. 41-10-х-х=81
31-2х=81
2х=31-81
2х= -50
х= -50:2
х= -25

6. 9х-4х=135-30
5х=105
х=105:5
х=21

8. 45+30=112-х
х=112-45-30
х=37

9. 8у+3у=77
11у=77
у=77:11
у=7

10. 2а+3а+10а-4а=11а
при а =10
11*10=110