Can somebody please help me with this?

Answer:
[tex]\sqrt{85}\ units[/tex]
Step-by-step explanation:
The figure shows the right triangle with two legs a and b and hypotenuse c.
By the Pythagorean theorem,
[tex]\text{Hypotenuse}^2=\text{Leg}_1^2+\text{Leg}_2^2[/tex]
So,
[tex]c^2=a^2+b^2\\ \\11^2=6^2+b^2\\ \\121=36+b^2\\ \\b^2=121-36\\ \\b^2=85\\ \\b=\sqrt{85}\ units[/tex]