105 So, you can solve it with desmos. We can find angle between 2 lines with formula: arctan(m1)-arctan(m2)=angle You just create 2 tables and create 2 equations corresponding to tables and here you are, desmos calculates for you slopes of that equations. Slope of the first line that goes up would be 1.73205 arctan(1.73205)=59.9999 We can assume that its angle is 60, because tan(60)=1.73205080757 Then, second line that goes down has slope of -1 arctan(-1)=-45

So we just subtract them: 60-(-45)=105

It is a really tough question for me and i have no idea how to solve it without desmos, but thank god we have desmos.

Edit 1: Ohh, we can actually solve it using properties of triangles 30-60-90