Answer :
Since all sides of the rhombus are equal, then we can formulate the following equation:
2p + 9 = 3p - 6
2p + 9 +6 = 3p ( Adding 6 to both sides of the equation)
9+6 = 3p - 2p (Subtracting 2p from both sides of the equation)
15 = p (Adding like terms)
Replacing p=15 in the equation of side DO, we have:
DO= 2*(15) + 9
DO= 30 + 9 (Multiplying)
DO = 39 (Adding)
Since all sides of the rhombus are equal, then we conclude that GS is equal to 39.