1)

3b + 28

------------ = 4

   25

(3b + 28) : 25 = 4

3b + 28 = 4 * 25

3b + 28 = 100

3b = 100 - 28

3b = 72

b = 72 : 3

b = 24

2)

3а

---- = 15

4

3а : 4 = 15

3а = 15 * 4

3а = 60

а = 60 : 3

а = 20

3)

16а - 24

------------- = 12

      6

(16а - 24) : 6 = 12

16а - 24 = 12 * 6

16а - 24 = 72

16а = 72 + 24

16а = 96

а = 96 : 16

а = 6

4)

29b + 172

--------------- = 5³

      3

(29b + 172) : 3 = 5³

29b + 172 = 5³ * 3

29b + 172 = 125 * 3

29b + 172 = 375

29b = 375 - 172

29b = 203

b = 203 : 29

b = 7

Verified answer

1)3б+28=4*25

3б+28=100

3б=100-28

3б=72

б=72:3

б=24

2) 3а=15*4

3а=60

а=60:3

а=20

3) 16а-24=12*6

16а-24=72

16а=72+24

16а=96

а=96:16

а=6

4) 29б+172=5³*3

29б+172=125*3

29б+172=375

29б=375-172

29б=203

б=203:29

б=7