As it seems a little extreme for so much XP to be spent on /1/ language when you go up in linguistics, we’ve worked out a percentage system. 

• Ling 1 – 1 language
• Ling 2 – 1 more language
• Ling 3 – 2 more languages
• Ling 4 – 3 more languages
• Ling 5 – 4 more languages

After that, each additional language costs 2 XP.