Answer:
9
Step-by-step explanation:
To solve this question you need the formula of hypothenuse theorem, I personally use [tex]a^{2} + b^{2} = c^{2}[/tex].
Since [tex]c^{2}[/tex] is the hypothenuse, and the hypothenuse in this case is 15, the equation will be [tex]12^{2}+ b^{2} = 15^{2}[/tex].
144+[tex]b^{2}[/tex]=225
subtract 144 from both sides
[tex]b^{2}[/tex]= 81
[tex]\sqrt{b^{} } = \sqrt{81}[/tex]
b=9
