10 points someone help me please!?

Answer:
[tex]\large\boxed{b=\sqrt{95}}[/tex]
Step-by-step explanation:
Use the Pyhagorean theorem:
[tex]leg^2+leg^2=hypotenuse^2[/tex]
We have
[tex]leg=b,\ leg=7,\ hypotenuse=12[/tex]
Substitute:
[tex]b^2+7^2=12^2[/tex]
[tex]b^2+49=144[/tex] subtract 49 from both sides
[tex]b^2=95\to b=\sqrt{95}[/tex]