At least 15 b/c is you add QWERTY to -12, you get zero and adding 5 to get 15 in total.
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
:)
Step1: group the first two terms together
next step 2:factor out a GFC from each separate binomical
next step 3: factor out the common binomial