This diagram gives you many big hints.
Can you find reasons and explanations for how it all fits together
as it appears to do?
It is important to bear in mind that the angles around a point add
up to $360^o$ and the angles on a straight line make $180^o$.
When you have found the angles in the quadrilaterals does this
suggest that the quadrilaterals are a special type?
See how $3$ copies of triangle $D$ and two chosen from triangles
$r, s$ and $t$ fit into the quadrilaterals like pieces of a jigsaw.
Can you explain why it works?