in a rhombus, its diagonals meet at right-angles, namely all angles at Q are all right-angles, and also the diagonals cut each other in two equal halves.
what the dickens does all that mean? well, it means that PQ = QA, since the diagonal MC is cutting PA in two equal halves, therefore
[tex]\bf \stackrel{PQ}{x+2}~~=~~\stackrel{QA}{3x-14}\implies 16=2x\implies \cfrac{16}{2}=x\implies 8=x
\\\\\\
PA\implies PQ+QA\implies (8)+2~~+~~3(8)-14\implies 10+24-14
\\\\\\
34-14\implies 20[/tex]
