`3/4b = 1/4b+3 || -1/4b `

`2/4b = 3 || T `

`1/2b = 3 || *2 `

`b=6 `

Probe:

`3/4*6 = 1/4*6+3 `

`9/2 = 3/2+6/2 `✔✔

`=> L={6} `