What would BI be? I don’t get it

Answer:
34
Step-by-step explanation:
Of I is the incenter then : AI, BI, and CI would be equal
if lengths are equal we can make an equation to solve the length of BI
AI = BI ➡ 3x+7 = 5x-11 ➡ 2x = 18 ➡ x = 9
replace x with 9
5x-11 ➡ 5×9-11 = 34