Calculation of the genotype likelyhood

Question

[Gama313]

I am struggling with this task since I am not able to calculate the genotype likelihood from row data. In particular, i have raw counts (A:5,C:100 ..) and quality scores associated to each base called assuming that the mapping quality is the highest. I read hundreds of post, but there is no clear step-by-step explanation to calculate this parameter for specific positions. I thank in advance anyone who will help me.