I'm assuming you mean that <C=68 degrees.
Now we know that the interior angle of a triangle adds up to 180 degrees.
We just need to subtract the 2 already known angles from it.
180 degrees-56 degrees-68 degrees=180 degrees-124 degrees=56 degrees.
Done!
<B=56 degrees.
Any questions you can ask in the comments, also something to look out for always capitalize your letter when you are writing angles :)!
