keeping in mind that in a parallelogram the diagonals bisect each other, namely cut each other into two equal halves. Check the picture below.
![\stackrel{GH}{3x-4}~~ = ~~\stackrel{HE}{5y+1}\implies 3x=5y+5\implies x=\cfrac{5y+5}{3} \\\\[-0.35em] ~\dotfill\\\\ \stackrel{DH}{x+1}~~ = ~~\stackrel{HF}{3y}\implies \stackrel{\textit{substituting "x" in the equation}}{\cfrac{5y+5}{3}+1~~ = ~~3y}](https://tex.z-dn.net/?f=%5Cstackrel%7BGH%7D%7B3x-4%7D~~%20%3D%20~~%5Cstackrel%7BHE%7D%7B5y%2B1%7D%5Cimplies%203x%3D5y%2B5%5Cimplies%20x%3D%5Ccfrac%7B5y%2B5%7D%7B3%7D%20%5C%5C%5C%5C%5B-0.35em%5D%20~%5Cdotfill%5C%5C%5C%5C%20%5Cstackrel%7BDH%7D%7Bx%2B1%7D~~%20%3D%20~~%5Cstackrel%7BHF%7D%7B3y%7D%5Cimplies%20%5Cstackrel%7B%5Ctextit%7Bsubstituting%20%22x%22%20in%20the%20equation%7D%7D%7B%5Ccfrac%7B5y%2B5%7D%7B3%7D%2B1~~%20%3D%20~~3y%7D)

S
The correct answer is the third one
<span>-3(1+6r)=14-r
-3 - 18r = 14 - r ...expand by using distributive property
-3 -17r = 14 ...add (r) to both sides
-17r = 17 ...add (3) to both sides
r = -1 ....divide both sides by (-17)</span>
Answer:
C is the answer according to me