public string SkillBonus(int skillId) { var skill = Skills.Single(n => n.Id == skillId); var bonus = AbilityScores.Single(n => n.AbilityId == skill.AbilityId).Bonus; var proficiencyBonus = PlayerSkills.Contains(skillId) ? _ProficiencyBonus : 0; var total = bonus + proficiencyBonus; return((total >= 0 ? "+" : null) + total.ToString()); }