Given, 2x−3y−7=02x−3y=7 On taking power 3 both the sides, we get (2x−3y)3=73 ⇒(2x)2−(3y)3−3(2x)2(3y) +3(2x)(3y)2=343 [∵(a−b)3=a3−b3 −3a2b−3ab2] ⇒8x3−27y3−36x2y +54xy2−343=0 ⇒8x3−36x2y+54xy2 −27y3−340=3 Hence, the value of the given expression is 3 .