Please help, I just started trig. Thanks!

About 3.052 units

Step-by-step explanation:

I  presume you won't  need this explanation now,  but just in case;

If we draw triangle MNK, as  MN = NK we know is isosceles. Now let's draw an altitude to MK so that  it splits MK into two congruent parts (5/2 = 2.5). Given M<N = 110 degrees the altitude would split the angle into two congruent angles as well (Coincidence Theorem) 110/2 = 55 degrees.

Now let's study the smaller triangles, and take one as an example. Remember sin(theta) = opp/hyp. Applying this we have theta as 55 degrees, the opposite side as 2.5, and the hypotenuse is yet to be found (MN);

sin(55°)= 2.5/MN,

x = 2.5/sin(55°) ≈3.052