We can use the ratios for special triangles (see the attachment below). We'll be using the 45-45-90 triangle. We notice that side BC is equal to

, and side AC (x using the special right triangle) is equal to 16. We can therefore say that side BC is equal to

ft
:)
I can't really help without the amounts being given but I can say that two supplementary angles add up to 180 degrees, so I hope that helps