PQ = X1 = 15 m.
X2 = hor. distance from Q to kite.
Tan45 = h/X2
h = X2*Tan45
Tan35 = h/(X1+X2)
h = (X1+X2)*Tan35 = (15+X2)*Tan35
X2*Tan45 = (15+X2)*Tan35
X2 = 10.5 + 0.7X2
0.3X2 = 10.5
X2 = 35 m.
h = X2*Tan45 = 35 * Tan45 = 35 m.
h = (X1+X2)*Tan35 = 50*Tan35 = 35 m.
what is the diagram for this
clearly, it's a triangle involving a kite at height h, and two observers,
Q at x1 and another at x2, farther away.
This must just be a test post. For you to have done all that math, you must have already had a diagram.